GMAT Sentence Correction (SC) | Re: Standard police procedure requires that an officer interview

after reading all the posts,

i still believe that "C" is the right answer.

(C) Standard police procedure requires an officer to interview witnesses separately rather than 'to interview them' together

in this sentence, if you remove the word "to interview them", then it will be perfect,
but still its correct as i think.

correct me if i m wrong.!