---I’m sorry for losing your book. I will buy a new one for you.-. I have another copy.

问题补充：

---I’m sorry for losing your book. I will buy a new one for you.

---. I have another copy.

A. Thank you

B. Happy to hear that

C. Never mind

D. Of course

答案：

A. Thank you

B. Happy to hear that

(答案→)C. Never mind

D. Of course

解析：情景交际。Thank you 谢谢你；Happy to hear that 很高兴听到那个消息； Never mind不要介意； Of course当然了。句意：很抱歉丢了你的书。我给你买本新的。结合下文，我还有一本呢。可知选C，最符合语境。