Answer:
The correct sentence is:
C. Fashion, Inc. had already shipped the order before Mr. Chu requested it be canceled.
The sentence is in the past perfect tense, which is appropriate for describing an action that occurred before another action in the past. In this case, "had already shipped" indicates that the shipping occurred before Mr. Chu's request for cancellation. The other options do not fit the context as they do not indicate the sequence of events in the past as precisely as the past perfect tense does.