To maintain a high demand for their product, the manufacturers first took over the marketing and sales functions previously performed by outside agents; next, they began changing their advertising campaigns monthly to keep pace with the rapid changes in consumers’ lives.

(A) they began changing

(B) this began changing

(C) the former began changing

(D) to begin changing（A）

(E) to change

这里的they没有指代歧义的问题吗？我选了C，虽然读起来很别扭，但是为了避免指代不清，我还是选了它。

former不是也有制造者的意思嘛．

不是用former更好？！为什么不选Ｃ

former做名词指代前者，你从字典哪里得到former=manufacturer?

再说即使是等同于manufacturer，也得用复数啊.MM好强，这思维都有，呵呵

 一点感想

gmat里面没有绝对的定式，每条rule都有exception。

比如这里就说明they的指代不清的劣势不一定总是让它成为最差的选项，这里C里面的the former并不能让指代变得跟清晰，而这里另一个逻辑结构first...next...帮助了they来clarify它的标的。但是与the former相比，they的简洁的优势就显示出来了。