a SC question from Kaplan

applebees

A common social problem in the workplace occurs when workers accept supervisory positions, and it causes them to lose the trust of their former coworkers.
(A)
(B) when workers accept supervisoty positions, and so lose
Why the answer is B?

1stzhang

cause的动作发起是前面的那个句子产生的结果。it不能指代句子

applebees

But can't "it" refer to "problem" rather than the whole sentence?

1stzhang

如果是it指带problem,it也是多余的,应该写成
A common social problem in the workplace occurs when workers accept supervisory positions and causes them to lose the trust of their former coworkers.
显然B更合理