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

#include<iostream>
using namespace std;
 
int main()
{
   int x = 10;
   int& ref = x;
   ref = 20;
   cout << x << endl ;
   x = 30;
   cout << ref << endl;
   return 0;
}

A. A variable that stores the size of another variable B. A variable that stores the address of another variable C. A variable that stores a reference to another variable D. None of the above

A. ptr *type; B. type ptr; C. type *ptr; D. ptr type;

A. Address of x B. Garbage value C. Compilation error D. 5

A. *ptr B. ptr* C. &ptr D. ptr