Which of the following is the correct way to call the function MyFun() of the Sample class given below?

class Sample
{
    public int MyFun(int i)
    {
        Console.WriteLine("Welcome to CuriousTab.com !" );
        return 0;
    }
}

delegate void del(int i);
Sample s = new Sample();
deld = new del(ref s.MyFun);
d(10);

delegate int del(int i);
Sample s = new Sample(.);
del = new delegate(ref MyFun);
del(10);

Sample s = new Sample();
delegate void del = new delegate(ref MyFun);
del(10);

delegate int del(int i);
del d;
Sample s = new Sample();
d = new del(ref s.MyFun);
d(10);