What will be the output of the following C# code?

class maths
{
    public static void fun1()
    {
        Console.WriteLine("method 1 :");
    }
    public void fun2()
    {
        fun1();
        Console.WriteLine("method 2 :");
    }
    public void fun2(int k)
    {
        Console.WriteLine(k);
        fun2();
    }
}    
class Program
{
    static void Main(string[] args)
    {
        maths obj = new maths();
        maths.fun1();
        obj.fun2(20);
        Console.ReadLine();
    }
}

A. method 1:
method 2:
20
method 1:

B. method 2:
20
method 1:
method 1:

C. method 1:
0
method 2:
method 2:

D. method 1:
20
method 1:
method 2:

Answer: Option D