What is the output of this program?

#include<stdio.h>
#include<fcntl.h>
 
int main()
{
    int fd;
    char buff[512];
    if( mkfifo("/tmp/test_fifo",0666) == -1)
        perror("mkfifo");       
    fd = open("/tmp/test_fifo",O_RDONLY);
    read(fd,buff,512);
    printf("%s\n",buff);
    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