What Is the Output of the Following Program?
#Include $\quad$

Multiple Choice

What is the output of the following program?
#include <iostream>
using namespace std;
class TestClass
{
$\quad$ public:
$\quad$$\quad$ TestClass(int x)
$\quad$$\quad$ { cout << x << endl; }
$\quad$$\quad$ TestClass()
$\quad$$\quad$ { cout << "Hello!" << endl; }
};
int main()
{
$\quad$ TestClass test;
$\quad$ return 0;
}

A) The program runs, but with no output.
B) 0
C) Hello!
D) The program will not compile.