C Potential Interview Question Too hard

Question

Determine which Foo method will be invoked without running the code:

class A
{
   public void Foo( int n )
   {
      Console.WriteLine( "A::Foo" );
   }
}

class B : A
{
   /* note that A::Foo and B::Foo are not related at all */
   public void Foo( double n )
   {
      Console.WriteLine( "B::Foo" );
   }
}

static void Main( string[] args )
{
   B b = new B();
   /* which Foo is chosen? */
   b.Foo( 5 );
}

Which technique? Then why? Run the code without trying to trick it.

I came across this problem online, and I think I'll use it as a question in an interview because I enjoy it. Link: http://netpl.blogspot.com/2008/06/c-puzzle-no8-beginner.html