41.

What is the output:

static void Main(string[] args)
{
    string test = "Welcome to studentboxoffice.in";
    ChangeString(test);
    Console.WriteLine(test);
}

static void ChangeString(ref string str)
{
    str = "Goodbye studentboxoffice.in";
}

"ref" keyword needs to be placed in the method call i.e., ChangeString(ref test);