Sentence Correction

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
(E) to change

OA :A

what makes C wrong , isn't "they" ambiguous in choice A ?

Since the sentence contains semicolon, "next, they began.." is an independent clause. They here refers to the subject of the previous clause, which is "the manufacturers".

Check this post. it may help you.
https://www.beatthegmat.com/pronoun-erro ... tml#267168

C is wrong because its wordy.

Hope that helps..