how to arraylist item controller to view using json in mvc4

public JsonResult LoadChild()
        {
            DataTable dt = new DataTable();
            SqlConnection con = new          SqlConnection(ConfigurationManager.ConnectionStrings["DB"].ConnectionString);
            string qry1 = "Select * from tbTest";
            SqlCommand cmd = new SqlCommand(qry1,con);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            da.Fill(dt);
            
            ArrayList list3 = new ArrayList();
            foreach (DataColumn dr2 in dt.Columns) // dt- DataTable
            {
                list3.Add(dr2);

                
            }
            return Json(list3, JsonRequestBehavior.AllowGet);
        }

<script>
function LoadChild()
    {
        $(document).ready(function ()
        {
            $.ajax({
                    type: "GET",
                    contentType: "application/json; charset=utf-8",
                    url: "/AddModule/LoadChild",
                    data: {},
                   dataType: "json",
                     success: function (data)
                    {
                       
                        alert(data); 
                     
                       
                    },
                    error: function (result) {
                        alert("hello Error");
                    }
                });
            });
    }
</script>