Which sentence uses past perfect tense correctly?

• A. Sam had worked at a university before he decided to become an actor.
• B. Sam had been working at a university before he decided to become an actor.
• C. Sam had decided to become an actor before he had worked at a university.
• D. Sam will have worked at a university before he decided to become an actor.

Answer: (A)

Past perfect tells us that one past action happened before another past action. In a two-event sequence like this, the earlier action should be in past perfect and the later one in simple past.

The best sentence uses had worked to show that the stint at the university was completed before the decision to become an actor was made. This cleanly places the university work earlier than the decision, with the decision described in simple past.

The other options change the nuance or the timing: using had been working suggests a duration up to the decision, which isn’t necessary here and shifts emphasis; saying he had decided before he had worked reverses the order of events; and will have worked describes a future-perfect situation, which doesn’t fit a past-time context.