Which question has the wh-word functioning as the object rather than the subject?
Who inspected the fire doors?
Which valve failed overnight?
What caused the vibration?
What did the design team approve?✓Правильный ответ
Объяснение
In the keyed sentence, the design team is the stated subject and what receives the action of approve. In each distractor, the wh-expression itself names the unknown doer or cause directly before the verb.