What is the output of this C++ program?
#include <iostream>
using namespace std;
void square (int *x)
{
*x = (*x)++ * (*x);
}
void square (int *x, int *y)
{
*x = (*x) * --(*y);
}
int main ( )
{
int number = 30;
square(&number, &number);
cout << number;
return 0;
}

A

910

B

920

C

870

D

900