Which of the following process state transitions is/are NOT possible?

Correct answer: Waiting to Running and Ready to Waiting are not possible directly.

• Why Waiting to Running is not possible: A waiting (blocked) process is waiting for an event (e.g., I/O). When the event completes the process becomes ready; it cannot skip the ready state and go directly to running because the scheduler must dispatch it.

• Why Ready to Waiting is not possible: A ready process is not executing, so it cannot perform an action (like initiating I/O) that would cause it to block. It must first be dispatched to running; only while running can it block and move to waiting.

• Why Running to Ready is possible: A running process can be preempted (time slice expires or a higher-priority process becomes runnable) and moved to the ready state.

• Why Running to Terminated is possible: A running process can complete execution or call exit and move directly to the terminated state.