Step 1: Active to passive.
Active: "When do you drink coffee?"
Passive: "When is coffee drunk by you?" (Correct tense and word order).
Step 2: Checking options.
(A) Wrong — incorrect word order.
(B) Correct — "When is coffee drunk by you?"
(C) Wrong — awkward form.
(D) Wrong — changes tense to past.
Step 3: Conclusion.
Correct answer is (B) When is coffee drunk by you?.