John Smith provides information on the conditions that lead women to a gynecologist, and he notes that these conditions can, and sometimes are, used in the promotion of surgery which is not needed.

A. and he notes that these conditions can, and sometimes are, used in the promotion of surgery which is not needed

B. noting that these conditions can be, and sometimes are, used to promote needless surgery

C. and notes that they could and sometimes are used unnecessarily in promoting surgery

D. sometimes promoting needless surgery

E. which they use sometimes to promote unnecessary surgery

I checked the right answer. my question is that, if in option C instead of they be there is that sentence also be correct? what is wrong with option C beside the they