Match each operating-system activity in List I with its commonly associated…

Concept

A scheduling discipline is selected according to the resource and service pattern being managed. Queue-based workloads use an order suited to arrival or urgency, while interactive and storage workloads use policies designed for fairness or head movement.

The association is made by identifying the defining mechanism of each activity, not by treating every named discipline as a CPU-scheduling algorithm.

Application

1. Disk scheduling uses SCAN: the disk head services requests while moving in one direction and then reverses, like an elevator.

2. Batch processing uses FIFO: jobs are ordinarily handled in their arrival order in the basic batch-queue model.

3. Time sharing uses round-robin: each ready process receives a time quantum in cyclic order.

4. Interrupt processing uses LIFO in the standard nested-interrupt model: the most recently entered interrupt service context completes first.

Cross-check and contrast

• SCAN is tied to disk-head movement rather than to cyclic CPU time slices.

• FIFO captures arrival-order batch service rather than nested interrupt returns.

• Round-robin provides repeated time slices, which is the defining service pattern of time sharing.

• LIFO matches the stack-like return order of nested interrupt handling.

Therefore, (a), (b), (c), and (d) match 2, 4, 1, and 3 respectively, so the required sequence is 2, 4, 1, 3.