His parents were on tenterhooks

His parents were on tenterhooks all the time until they got his letter.
A、他的父母在收到他的信之前一直心烦意乱。
B、他的父母一直心烦意乱从收到他的信时。
C、他的父母在收到他的信后一直心烦意乱。
D、他一直心烦意乱在父母在收到他的信之前。
【正确答案】：A
【题目解析】：p120