The past perfect tense is used to describe an action that occurred:

The past perfect tense is specifically used to indicate that one action was completed before another action took place in the past. This helps establish a clear chronological order of events, making it easier for readers to understand which action occurred first. For instance, in the sentence "She had finished her homework before the movie started," the phrase "had finished" signifies that the homework was completed prior to the movie starting, clearly situating the actions in time.

In contrast, the other choices describe different relationships between actions. Describing actions occurring at the same time or after another action would typically involve other tenses, such as the simple past or past progressive, which do not convey the same sequence of completed actions. Saying an action occurs in the future is not applicable in the context of past perfect tense, as it is specifically concerned with actions completed in the past relative to other past actions.