He has been living in Paris ______ 2010.

• A. For
• B. During
• C. Since
• D. By

Answer: (C)

This is about showing when an ongoing action began in the past and continues now. With has been living, the action is happening from the past up to the present, so we need a starting point. Since is the natural choice because it marks the exact time the action started: 2010.

For would require a length of time (for example, for ten years) rather than a specific starting point. During refers to a period or span, not the point at which the action began. By is used to indicate a deadline or something completed by a certain time, which doesn’t fit an ongoing situation starting in the past.