The PRIMARY DISADVANTAGE of FIFO scheduling is

1. OSTEP §7.3 names the CONVOY EFFECT: if a long-running job (cargo ship 'A') is at the head of the queue, all shorter jobs behind it must wait for the entire long run to finish. 2. Result: average turnaround time is dominated by the long job's run time, regardless of how short other jobs are. 3. Example: jobs with run times $100, 10, 10$ have average turnaround $110$ under FIFO — much worse than SJF's $50$. 4. Option A is wrong — FIFO has LOW context-switch overhead (no preemption). Options C, D don't apply to FIFO. _Source: OSTEP Ch 7, §7.3 (FIFO — convoy effect), p. 3._