In the following question, the sentence is given in the active voice. Select the option that expresses the same idea in the passive voice: Who teaches you Mathematics?

Introduction / Context:
This question checks understanding of the transformation from active voice to passive voice in English grammar, specifically in interrogative sentences. The original sentence is a present simple question about the person who performs the action of teaching. To answer correctly, we must preserve the tense, meaning and sense of enquiry while changing the structure from active to passive. This is a common type of question in competitive examinations and language tests.

Given Data / Assumptions:
- Active voice sentence: Who teaches you Mathematics? - Subject in the active sentence is the unknown person referred to by who. - Object in the active sentence is you, and Mathematics is the direct object of the verb teach. - The tense is present simple, indicating a regular or habitual action.

Concept / Approach:
To change an active sentence to passive, we promote the object of the active sentence to the subject position in the passive sentence. The main verb is changed to a form of be followed by the past participle of the original verb. The original subject is usually introduced by the preposition by. In interrogative sentences, we must also maintain correct question word order. For present simple passive, the structure is: am or is or are plus past participle. Since the subject in the passive will be you, we will use are taught. The question also uses who as a subject, which in passive form becomes by whom, placed at the beginning of the sentence.

Step-by-Step Solution:
Step 1: Identify the object that will become the new subject. In the active sentence, you is the indirect object receiving the teaching. In the passive form, you will come to the subject position. Step 2: Retain the tense. The present simple of teach becomes are taught when used in the passive with subject you. So the core passive structure is you are taught Mathematics. Step 3: Convert the question pattern. The active question begins with who because the doer is unknown. In the passive question, the doer becomes an agent introduced with by, so who changes to by whom at the start of the sentence. Step 4: Combine the elements in proper interrogative order: By whom are you taught Mathematics? This keeps the auxiliary are before the subject you, which is required in questions. Step 5: Check that the meaning remains the same. The new sentence still asks for the identity of the person who teaches you Mathematics, but now expressed in passive voice.

Verification / Alternative check:
We can confirm by reversing the passive sentence back to the active. From By whom are you taught Mathematics? we can reconstruct the active form as Who teaches you Mathematics? This matches the original question exactly in meaning and tense. Also note that the tense has not changed to past or future, and no extra words have been added that alter the sense of regular teaching. This confirms that the chosen option correctly represents the passive form.

Why Other Options Are Wrong:
Option B: By whom were you taught Mathematics? changes the tense from present simple to past simple, which changes the meaning to a question about previous teaching, not current or habitual teaching. Option C: By whom will you be taught Mathematics? shifts the tense to future, which again does not match the original meaning. Option D: Mathematics is taught by whom? is grammatically awkward and does not follow the standard pattern for polite questions in English. It also fails to show that you is the person being taught.

Common Pitfalls:
Learners often forget to maintain tense when changing voice and may choose a past or future form simply because it sounds natural. Another frequent mistake is placing by whom at the end rather than at the beginning in formal English, which can sound incorrect or very informal. It is important to remember that interrogative passive forms require the auxiliary before the subject and the question phrase at the start. Practising transformations both from active to passive and back helps to fix these patterns in memory.

Final Answer:
The correct passive form of the sentence is By whom are you taught Mathematics?, so option A is correct.