最好留下句子解释

题目

最好留下句子解释
When you want your parents to let you do something,you will have better success ------- you ask before you really start doing it.
A）since
B）if
C)beacuse
D)though

答案

应该选B吧?
当你要你的父母允许你做什么事的时候,如果你先请求他们再开始做,那么你会更加成功.