HELP!!! why my answer is incorrect?

Question

Fill in the blanks to create a function that concatenates strings and returns the result.

static string Concat(string x, string y)
{
string res = x + y; //<-- that is the incorrect answer
return res;
}
string msg = Concat ("Finishing ", "the last module");
Console.WriteLine(msg);

Answer 1

It was a lesson in the C# course that was poorly coded in an exercise, my answer was correct but it didn't accept it. Anyway, I was able to solve it now. Thanks for your contribution!

Answer 2

Add this in your Program Class, and then it will work.

static string Concat(string x, string y)
{
string res = x + y;
return res;
}

static void Main(string[] args)
{
string msg = Concat("Finishing ", "the last module");
Console.WriteLine(msg);

}