Let’s examine the sentence: “I was glad we ____ the candles when the lights went out.” All the verbs in the sentence are of past tense and the sentence states an action that had already occurred ‘when the lights went out.’’ So, the sentence talks about an action that was completed in the past. To convey this sense, the sentence requires verbs of past perfect tense. Past perfect tense indicates that an action was completed (finished or "perfected") at some point in the past before something else happened. This tense is formed with the past tense form of "to have," i.e. had, plus the past participle of the verb. Option D is the only choice containing the verb ‘had’ and the past participle of ‘had’ in the sense of ‘owning’. So it is the correct answer. Option A cannot be used as it contains the verb ‘has,’ which is used in present perfect tense and not past perfect tense. Options B and C cannot be used as they would make the sentence grammatically incorrect.