Match List I (Process state transition) with List II (Reason for transition),…

A process cycles between three states -- Ready, Running, and Blocked -- and each move between them is caused by exactly one kind of scheduler or I/O event: the short-term scheduler DISPATCHES a Ready process onto the CPU to make it Running; a Running process is PRE-EMPTED (the scheduler forcibly takes the CPU back) and returns to Ready; a Running process itself RAISES A WAIT request for some resource or another process's action and moves to Blocked; and a Blocked process returns to Ready only once the specific request or event it was waiting for is SATISFIED.

Applying this rule to each pair in the question:

1. (a) Ready → Running happens when the process is dispatched onto the CPU -- reason (iii).

2. (b) Blocked → Ready happens once the event/request the process was waiting for is satisfied -- reason (i).

3. (c) Running → Blocked happens when the process itself raises a wait request for another process's action -- reason (ii).

4. (d) Running → Ready happens when the process is pre-empted by the scheduler -- reason (iv).

So the full match is (a)-(iii), (b)-(i), (c)-(ii), (d)-(iv), i.e. the sequence iii, i, ii, iv.

Cross-check: each of the four reasons (i)-(iv) is used exactly once across the four transitions, and no reason is left over or repeated -- confirming this is a complete, one-to-one match consistent with the standard three-state process model (Ready ⇄ Running ⇄ Blocked, with Ready ⇄ Running being the only direct link between those two states).