They will finish the project ______ time if they work harder.

• A. On
• B. In
• C. At
• D. By

Answer: (A)

This item tests the choice of preposition with time when talking about completing something by a deadline. Finishing the project on time means meeting the due time exactly, i.e., not late. The sentence also uses a real conditional: they will finish the project on time if they work harder, which fits the idea that increased effort could help them meet the deadline.

Using in time would be less natural here because it emphasizes just being in time to avoid being late in a broader sense, rather than specifically meeting a deadline. At time isn’t used with finish+time in this context, and by time would require a different phrasing like by that time or by the deadline. So the natural, common expression for this situation is finishing on time.