A sentence has been given in the active voice; out of the four alternatives, select the option that best expresses the same idea in the passive voice: Why did your mother write such a book?

Introduction / Context:
This question tests your understanding of converting a question from active voice to passive voice. The original active question is Why did your mother write such a book. You must preserve both the tense and the interrogative structure while changing the focus from the agent your mother to the object such a book.

Given Data / Assumptions:
The active sentence uses the auxiliary did to mark simple past tense and places the subject your mother before the main verb write. In passive voice, the object such a book should become the subject, and your mother should appear in a by phrase. The tense must remain in the simple past, and the question word why must stay at the beginning.

Concept / Approach:
To change a simple past question in active voice to passive voice, we follow a clear pattern. The object moves to the subject position, the auxiliary be takes the same past tense form was, and the main verb takes the past participle written. The agent your mother is added after by. The standard structure therefore becomes Why was such a book written by your mother.

Step-by-Step Solution:
Step 1: Identify the object in the active sentence, which is such a book.Step 2: Move this object to the subject position in the passive sentence.Step 3: Replace did write with the passive combination was written to keep the simple past tense.Step 4: Add the preposition by followed by the original subject your mother.Step 5: Keep why at the beginning to preserve the interrogative form, giving Why was such a book written by your mother.

Verification / Alternative check:
You can mentally reverse the passive form Why was such a book written by your mother back into active voice. Moving such a book after the verb and bringing your mother back to subject position yields Why did your mother write such a book, which matches the original sentence. This confirms that tense, meaning, and question order are preserved.

Why Other Options Are Wrong:
Why is such a book written by your mother uses is written, which is present tense, not simple past, so it changes the time reference. Why did your mother wrote such a book places wrote after did, which is grammatically wrong, since did must be followed by the base form write. Why was such a book wrote by your mother uses wrote instead of the past participle written after was and is therefore incorrect. For what reason did your mother write such a book is still in the active voice, so it does not satisfy the requirement to convert into passive voice.

Common Pitfalls:
Students sometimes forget to change the main verb to the past participle in passive structures or they change the tense unintentionally when they pick is instead of was. Others produce a correct passive clause but fail to keep the question word at the front, which spoils the interrogative form. Always check tense, verb form, and the presence of the question word when converting active questions to passive.

Final Answer:
The correct passive form of the sentence is Why was such a book written by your mother?