A. They
B. His
C. since
D. These
🧠 Explanation:
The sentence “I have not seen you since Monday” uses “since” to indicate a starting point in time for an ongoing situation. “Since” is appropriate for actions or states continuing from a specific moment, here implying the speaker hasn’t seen the person from Monday onward. Correct preposition use ensures clarity in temporal expressions, vital for effective communication. Misusing alternatives like “from” or “for” could obscure meaning. Mastering prepositions like “since” enhances precision in writing and speech, particularly in professional, academic, or casual contexts where accurate time references are essential for clear understanding.
