Mark the letter A, B, C, or D on your answer sheet to indicate the answer to each of the following questions
He’d finished doing his homework when you arrived, _______?
Correct Answer: EASY
The auxiliary verb “had” and the affirmative at the beginning of the question => the question tag will be in the negative form “hadn’t”.
Answer D (hadn’t he) is correct.
He finished all his homework when you arrived, didn’t he?