What is the output of this when the pipe is successfully created?

#include<stdio.h>
 
int main()
{
     int ret_val;
     int fd[2];
     ret_val = pipe(fd);
     printf("%d\n",ret_val);
     return 0;
}

A. countw B. wcount C. wc D. count p E. None of the above

A. dm B. rm C. delete D. erase E. None of the above

A. rdir B. remove C. rd D. rmdir E. None of the above

A. x B. y C. a D. z E. None of the above