单选题 It's a very kind offer, but I really ______ accept it.
A. mustn't B. needn't
C. can't D. don't

【正确答案】 C
【答案解析】[解析] mustn't语气强，“禁止”；needn't表示“不必”，常做must问句的回答：can't“不能”；don't助动词，无实意；通过句意可知答案为C。