Entity framework one to one relationship

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C#

entity-framework

I have a table of customers and Membershiptype

There is one to one relationship between customers and membershiptype table
customer table has foreign key of membershiptype table.

I have a code which is quite confusing but works fine to create a foreign key in customers table.

This is class for customer table

public class Customer
    {
        public int Id { get; set; }
        
        [Required(ErrorMessage="Please Enter Customer's name")]
        [StringLength(255)]
        public string Name { get; set; }

        public bool IsSubscribedToNewsLetter { get; set; }
              
        public MembershipType MembershipType { get; set; }

        [Display(Name = "Date of Birth")]
        [Min18YearsIfAMember]
        public DateTime? Birthdate { get; set; }
       
        
        [Display(Name="MembershipType")]
        public byte MembershipTypeID { get; set; }
        
    }
}

and the class for membershiptype table is

public class MembershipType
    {
        public byte Id { get; set; }

        public string Name { get; set; }
        public short SignUpFee { get; set; }
        public byte DurationInMonths { get; set; }
        public byte DiscountRate { get; set; }

        public static readonly byte unknown = 0;
        public static readonly byte PayAsYouGo = 1;
    }
}

What I have tried:

This most of the tutoirals in internet for one to one relationship use virtual and do not use the above stretegy for creating the forign key

the students table is holding the key for studentaccount table. and is using virtual.

public class Student

   {

      public int Id { get; set; }
      public string Name { get; set; }

      public int Age { get; set; }

      public virtual StudentAccount StudentAccount { get; set; }


   }

The student accounts table

public class StudentAccount
    {
        public int Id { get; set; }
 
        public string Name { get; set; }
 
        public int Amount { get; set; }
 
        [Required]
        public virtual Student Student { get; set; }
 
    }

What is the difference between two methods for these one to one relationships. and how these works in mapping the foreign key.