using System;

public class Program

{

    public static void Main()

    {

        Type a = typeof(A);

        Type b = typeof(B);

        Type c = typeof(C);

        Type d = typeof(D);

        Console.WriteLine(a.IsAssignableTo(typeof(A)));

        Console.WriteLine(b.IsAssignableTo(typeof(A)));

        Console.WriteLine(c.IsAssignableTo(typeof(A)));

        Console.WriteLine(d.IsAssignableTo(typeof(A)));

    }

}

​

class A {}

class B : A {}

class C : B {}

class D {} // not an "A"