The correct option is B taken
A tense is a form of a verb which provides derails about the action (timing, progress, completion, etc.). Option B) taken is correct as the principal clause uses the past perfect tense ( had + past participle) and therefore, only simple past tense can be used ( past participle of take) in the subordinate clause. The other options are wrong as no other tense can be used in the subordinate clause. The correct answer is B)taken.