Linda left school and went to work___her family.

Linda left school and went to work___her family.
A )for the sake of     B)because    C)since    Dby reason of
（sake --缘故）
That question why only select A.
for the sake of 是由于...的缘故   by reason of ---由于。这两个有什么区别吗，为什么选A而不选D呢？
为什么B和C也要排除呢。
I would like to know why.