单选题 I let my children make their own decisions _________ they're older: I wouldn't presume to interfere.

【正确答案】 A

【答案解析】now在此句中相当于连词now that“因为”，引导让步状语从句，表示原因时，比起because，since，as来要弱。B)、C)、D)三项均不符合题意。