Choose the option in which the given sentence has been correctly changed from Active Voice to Passive Voice.
Why didn’t he return your book?

Correct option is A

The correct answer is (a) Why wasn’t your book returned by him?
The given sentence is in Active Voice (simple past tense, negative–interrogative). While changing it into Passive Voice, the object “your book” becomes the subject, the tense remains simple past, and the question form is retained correctly.
• Definition (Active–Passive Voice):
Active Voice is used when the subject performs the action, whereas Passive Voice is used when the subject receives the action.
• Rule for change (English):
Active: Subject + did not + verb
Passive: Object + was/were not + past participle (V³)
The agent ( by him) may be mentioned or omitted.
• नियम (Hindi):
Active Voice में subject कार्य करता है, जबकि Passive Voice में subject पर कार्य होता है।
Simple past tense को passive में बदलते समय was/were + verb की तीसरी form का प्रयोग किया जाता है और प्रश्नवाचक रूप बना रहता है।
• Reason why other options are incorrect:
• (b) had not been changes the tense to past perfect.
• (c) Drops the agent and changes structure; though meaningful, it is not the most direct transformation.
• (d) Changes the subject–object meaning completely.
Thus, the correct option is (a).