--Would you mind opening the window? It’s too hot in the room. . I’ll do it right away.

问题补充：

--Would you mind opening the window? It’s too hot in the room.

-- . I’ll do it right away.

A. You ’ d better not

B. Of course not

C. I hope not

D. It doesn’t matter

答案：

A. You ’ d better not

(答案→)B. Of course not

C. I hope not

D. It doesn’t matter

解析：情景交际。You ’ d better not你最好别；Of course not当然不了；I hope not我希望不；It doesn’t matter没关系。根据上文，你介意我打开窗户吗？房间里太热了。联系下文，我正要做呢。可知选B最符合语境。