In the process management Round-robin method is essentially the pre-emptive…

Concept

CPU scheduling algorithms are often built as pairs: a queue-ordering discipline plus a preemption rule. First-Come-First-Served (FCFS) orders the ready queue by arrival time using FIFO order and runs each process to completion (non-preemptive). Round Robin keeps that same FIFO arrival order but adds a fixed time quantum and forced preemption, so it is described as the pre-emptive version of FIFO.

Application

1. Under FCFS, the ready queue is a FIFO structure: whichever process arrives first is scheduled first, and it runs until it finishes or blocks — there is no preemption.

2. Round Robin uses the identical FIFO arrival ordering for the ready queue.

3. Round Robin then adds ONE new rule on top of that FIFO order: each process runs for at most one fixed time quantum; if it has not finished, it is preempted and sent to the back of the same FIFO queue.

4. So Round Robin = FIFO ordering + time-quantum preemption, which is exactly what "the pre-emptive version of FIFO" means.

Cross-check

• FILO/LIFO is a last-in-first-out discipline (used for stacks), not the ordering Round Robin follows, so it cannot be the base algorithm being made preemptive.

• SSF orders processes by the smallest burst time value, which Round Robin never considers — RR is fully oblivious to burst length.

• "Longest time first" would order by the largest burst value, the opposite criterion from shortest-job policies and unrelated to arrival order.

Since Round Robin's only added rule over FCFS is preemption via a time quantum, and FCFS is defined by FIFO ordering, the correct answer is FIFO.