Givinig range in relationship for entity model in .NET Core

Question

I have two models with the relationship as below (i.e 1 to 1-3). i.e model class A has at least one but not more than 3 instance/record of class B. How will I specify this relationship?

public class A
{
    public int Id { get; set; }
    public string Name { get; set; }
    public ICollection<B> bbs{ get; set; }
}

public class B
{
    public int Id { get; set; }
    public A aa { get; set; }
}