Interface riddle

gistfile1.cs

   class Program
    {
        static void Main(string[] args)
        {
            IBar bar = new Bar();
            // Can you guess the output?            
            bar.Execute("TEST");
        }
    }


    public interface IFoo
    {
        void Execute(string value);
    }

    public interface IBar : IFoo
    {
        void Execute(object value);
    }

    public class Foo : IFoo
    {
        public void Execute(string value)
        {
            Console.WriteLine("Foo.Execute - string");
        }
    }

    public class Bar : IBar
    {
        public void Execute(string value)
        {
            Console.WriteLine("Bar.Execute - string");
        }

        public void Execute(object value)
        {
            Console.WriteLine("Bar.Execute - object");
        }
    }