You are sure to know the result，but that’s_______everybody has f

You are sure to know the result，but that’s_______everybody has finished their work.
A、when
B、why
C、before
D、until
【正确答案】：A
【题目解析】：考查表语从句的连接词。句意：你们一定会知道结果，但应是在每个人都完成他们的工作的时候。