What is the output? void IsEven (int num) { } int even; if (num % 2 == 0) { even 1; } else { even - } 0; int main(void) { IsEven (7); printf("%d", even); return 0; O a.0 O b. 1 O c. No output: Call to IsEven () fails due to no return value O d. No output: A compiler error occurs due to unknown variable even