The director wants to make sure no one will solve the mystery until it at the end of the

问题补充：

The director wants to make sure no one will solve the mystery until it at the end of the horror film.

A. is explained

B. will be explained

C. explains

D. has explained

答案：

(答案→)A. is explained

B. will be explained

C. explains

D. has explained

解析：句意：导演想确保在这部恐怖片的末尾揭示真相之前没有人能够破解这个谜团。Until引导的时间状语从句用一般现在时来表达将来时，it和explain存在着逻辑上的动宾关系；所以用被动结构；故选A。