56. In UNIX, the return value for the fork system call is _ for the child process and _ for the parent process.
a) A Negative integer, Zero
b) Zero, A Negative integer
c) Zero, A nonzero integer
d) A nonzero integer, Zero
Explanation: In Unix, the return value of the fork system call is Zero for the child process and Non-zero value for parent process. A fork system call returns the PID of a newly created (child) process to the parent and returns Zero to that newly created (child) process.