Q. What is the output of this program?

#include 
    using namespace std;
    int add(int p, int q);
    int main()
    {
        int n = 15, m = 16;
        cout << add(n, m) << endl;
        return 0;
    }
    int add(int p, int q )
    {
        int sum = p + q;
        p = 20;
        return p + q;
    }

• (A) 36
• (B) 15
• (C) 16
• (D) 20