Many-to-many relationship on the same table using a junction table and a primary key in EF - entity-framework

Question

I have the following tables:
Sub_Option: Sub_Option_ID as PK, Name
Sub_Option_To_Sub_Option: Sub_Option_To_Sub_Option_ID as PK, Sub_Option_ID_Primary, Sub_Option_ID_Secondary
I would like to be able to access all the secondary sub options associated with the primary sub option via EF and vice-versa. Directly using .Map won't work as the junction table Sub_Option_To_Sub_Option has a primary key.
public class Sub_Option
{
public int Sub_Option_ID { get; set; }
public string Name { get; set; }
}
corresponding to Table
CREATE TABLE Sub_Option(
Sub_Option_ID int,
Name varchar(255)
);
and Table
CREATE TABLE Sub_Option_To_Sub_Option(
Sub_Option_To_Sub_Option int PK,
Sub_Option_ID_Primary int,
Sub_Option_ID_Secondary int
);

Answer 1

This should work i think:
public class OptionToOption
{
[Key]
public int ID { get; set; }
[ForeignKey("PrimaryOption")]
public int PrimaryID { get; set; }
[ForeignKey("SecondaryOption")]
public int SecondaryID { get; set; }
public virtual Option PrimaryOption { get; set; }
public virtual Option SecondaryOption { get; set; }
}
public class Option
{
public Option()
{
OptionToOption = new HashSet<OptionToOption>();
}
[Key]
public int ID { get; set; }
public string Name { get; set; }
public virtual ICollection<OptionToOption> OptionToOption { get; set; }
}
And in fluent api map like this (don't even think it's necessary to do this though):
modelBuilder.Entity<Option>()
.HasMany(e => e.OptionToOption)
.WithRequired(e => e.PrimaryOption)
.HasForeignKey(e => e.PrimaryID);
modelBuilder.Entity<Option>()
.HasMany(e => e.OptionToOption)
.WithRequired(e => e.SecondaryOption)
.HasForeignKey(e => e.SecondaryID);