初中英语I'm sorry to have you waiting for so long for Marcia,and

初中英语I'm sorry to have you waiting for so long for Marcia,and I'm afraid it'll be ten minutes
I'm sorry to have you waiting for so long for Marcia,and I'm afraid it'll be ten minutes______she comes back.
A.before B.after C.until D.since
老师说选A,我的答案是选C.请问为什么until不行呢?
另外看了网上也有说选B的,那么就是说在M回来后还有10分钟了?还有什么将来时（it‘ll)对答案选择会有影响吗?