ASP.NET

 binding dropdown like Country,State,City..when im selecting any one country it showing me all country's state and city..

i want to show  country's related   State..and that state's related all City..pls help..what i want to do..

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Entity;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using MvcDdlStudCRUD.Models;

namespace MvcDdlStudCRUD.Controllers
{
    public class HomeController : Controller
    {
        private WorkTraningEntities db = new WorkTraningEntities();

        //
        // GET: /Home/

        public ActionResult Index()
        {
            var students = db.Students.Include(s => s.City).Include(s => s.Country).Include(s => s.State);
            return View(students.ToList());
        }

        //
        // GET: /Home/Details/5

        public ActionResult Details(int id = 0)
        {
            Student student = db.Students.Find(id);
            if (student == null)
            {
                return HttpNotFound();
            }
            return View(student);
        }

        //
        // GET: /Home/Create

        public ActionResult Create()
        {

            ViewBag.CityID = new SelectList(db.Cities, "CityID", "CityName");
            ViewBag.CountryID = new SelectList(db.Countries, "CountryID", "CountryName");
            ViewBag.StateID = new SelectList(db.States, "StateID", "StateName");
            return View();
        }

        //
        // POST: /Home/Create

        [HttpPost]
        public ActionResult Create(Student student)
        {

            if (ModelState.IsValid)
            {
                db.Students.Add(student);
                db.SaveChanges();
                return RedirectToAction("Index");
            }

            ViewBag.CityID = new SelectList(db.Cities, "CityID", "CityName", student.CityID);
            ViewBag.CountryID = new SelectList(db.Countries, "CountryID", "CountryName", student.CountryID);
            ViewBag.StateID = new SelectList(db.States, "StateID", "StateName", student.StateID);
            return View(student);
        }
        public JsonResult SelectStates(int id)
        {
            IEnumerable<State> states = db.States.Where(stat => stat.CountryID == id);
            return Json(states);
        }

        //
        // GET: /Home/Edit/5

        public ActionResult Edit(int id = 0)
        {
            Student student = db.Students.Find(id);
            if (student == null)
            {
                return HttpNotFound();
            }
            ViewBag.CityID = new SelectList(db.Cities, "CityID", "CityName", student.CityID);
            ViewBag.CountryID = new SelectList(db.Countries, "CountryID", "CountryName", student.CountryID);
            ViewBag.StateID = new SelectList(db.States, "StateID", "StateName", student.StateID);
            return View(student);
        }

        //
        // POST: /Home/Edit/5

        [HttpPost]
        public ActionResult Edit(Student student)
        {
            if (ModelState.IsValid)
            {
                db.Entry(student).State = EntityState.Modified;
                db.SaveChanges();
                return RedirectToAction("Index");
            }
            ViewBag.CityID = new SelectList(db.Cities, "CityID", "CityName", student.CityID);
            ViewBag.CountryID = new SelectList(db.Countries, "CountryID", "CountryName", student.CountryID);
            ViewBag.StateID = new SelectList(db.States, "StateID", "StateName", student.StateID);
            return View(student);
        }

        //
        // GET: /Home/Delete/5

        public ActionResult Delete(int id = 0)
        {
            Student student = db.Students.Find(id);
            if (student == null)
            {
                return HttpNotFound();
            }
            return View(student);
        }

        //
        // POST: /Home/Delete/5

        [HttpPost, ActionName("Delete")]
        public ActionResult DeleteConfirmed(int id)
        {
            Student student = db.Students.Find(id);
            db.Students.Remove(student);
            db.SaveChanges();
            return RedirectToAction("Index");
        }

        protected override void Dispose(bool disposing)
        {
            db.Dispose();
            base.Dispose(disposing);
        }
    }
}

<pre lang="text">    Your codeblocks should be of the form

    ```C#
/// avatar_resize
/// resizes an image that is a byte[] and return an image model
/// 
/// <param name="pName">Name of the Image</param>
/// <param name="pBytes">Byte Array of the image uploaded to the server</param>
/// <returns>model_image_object, with new resized byte array</returns>
public static model_image_object avatar_resize(string pName, byte[] pBytes)
{
    // Target Width / Height
    // Make a square image
    const int t_Width = 250;
    const int t_Height = 250;
    int cHeight = 0;
    int cWidth = 0;

    // Create the return Image Object
    model_image_object pResult = new model_image_object();
    MemoryStream stream_out = new MemoryStream();
    using (Stream stream_in = new MemoryStream(pBytes))
    {
        // Create an Image so we can get the image parameters
        Image image_in = Image.FromStream(stream_in);

        // Write this to the drive and visually inspect it, is it correct?
        //image_in.Save(System.Web.HttpContext.Current.Server.MapPath("~/Images/smtp/image_in.png"));

        // Figure out what we need to do to resize this image
        int oWidth = image_in.Width;
        int oHeight = image_in.Height;
        Color bgColor = Color.FromArgb(255, 255, 255);

        // Create the canvas for the new resized image
        using (Bitmap bitmapObj = new Bitmap(t_Width, t_Height, PixelFormat.Format24bppRgb))
        {
            // Create the new graphics, that will overlay the Bitmap Canvas
            using (Graphics graphicObj = Graphics.FromImage(bitmapObj))
            {
                graphicObj.Clear(Color.Transparent);
                graphicObj.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.Default;
                graphicObj.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

                // Calculate the new Height and Width of the Image
                if (oWidth == oHeight)
                {
                    cWidth = 250;
                    cHeight = 250;
                }
                else if (oWidth > t_Width)
                {
                    cWidth = t_Width;
                    cHeight = (int)Math.Round((oHeight / (float)oWidth) * t_Width);
                }
                else if (oWidth < t_Width)
                {
                    cWidth = (int)Math.Round((oWidth / (float)oHeight) * t_Height);
                    cHeight = (int)Math.Round((oHeight / (float)oWidth) * cWidth);    

                }
                else if (oHeight > t_Height)
                {
                    cHeight = t_Height;
                    cWidth = (int)Math.Round((oWidth / (float)oHeight) * t_Height);
                }

                // Calculate how to overlay the width of the image centered                        
                int x = (cWidth - t_Width) / 2;
                int y = (cHeight - t_Height) / 2;    

                // Create the new Image Object
                graphicObj.DrawImage(image_in, x, y, t_Width, t_Height);

                // Save the Graphic Object
                graphicObj.Save();
            }

            // Now write the image_out to test it and make sure it's correct, right size and placement            
            //bitmapObj.Save(System.Web.HttpContext.Current.Server.MapPath("~/Images/avatars/products/bitmap_out.png"));

            // Create a new MemoryStream to Save the Image to
            bitmapObj.Save(stream_out, ImageFormat.Png);
        }
    }

    // Program the pResult
    pResult.Data = stream_out.ToArray();
    pResult.Name = pName;
    pResult.Type = "image/png";
    pResult.Size = new model_image_type_size();
    pResult.Size.Height = cHeight;
    pResult.Size.Width = cWidth;

    return pResult;
}
    ```

public class model_image_object
    {
        public string Name { get; set; }
        public string Type { get; set; }
        public byte[] Data { get; set; }
        public model_image_type_size Size { get; set; }
    }