A. They had left before the storm started.
B. They left before the storm started.
C. They were leaving before the storm started.
D. They will leave before the storm starts.
Answer: They had left before the storm started.
A. They had left before the storm started.
B. They left before the storm started.
C. They were leaving before the storm started.
D. They will leave before the storm starts.
Answer: They had left before the storm started.
Additional Information: The past perfect tense describes an action completed before another action in the past.