P : In preemptive version of SJF$,$ even if the arriving process is shorter than currently executing process, current process is not stopped.

Q : On a multiprocessor, not only may process execution be interleaved, but also multiple processes can execute simultaneously.

a$.$ Q is wrong and P is correct

b$.$ P is wrong and Q is correct

c$.$ P and Q are true

d$.P$ and $Q$ are wrong