Which of the following CPU scheduling algorithms is non-preemptive, meaning a running process cannot be interrupted until it voluntarily releases the CPU?

First Come First Served (FCFS) is non-preemptive: once the CPU is allocated to a process, that process runs to completion (or until it blocks for I/O) before the next process in the queue is considered — it is never interrupted by a newly arriving process. Round Robin explicitly preempts a process when its time quantum expires. Shortest Remaining Time First (the preemptive version of SJF) preempts a running process if a shorter one arrives. Preemptive Priority Scheduling and Multilevel Feedback Queue Scheduling both allow a running process to be interrupted as well.