Unlike many of you, I don't see a problem with "to do". According to the MGMAT Sentence Correction
guide I'm reading, when the parallel structure contains 2 verb infinitives, the second "to" is optional. English is not my mother tongue, so it doesn't sound wrong to me as it may do for you, but I don't see the problem if they chose to insert the "to" here. Probably they just wanted to confuse as much as possible, because C is the only answer with "it" at the end.
From the below link, The OA is Option Chttp://www.urch.com/forums/gmat-sentenc ... tions.html
My answer was also Option E. Though i had read that in MGMAT book
about what cano has mentioned here, sometimes I get stumped for not applying what i had studied in problems.
Hope this question will help me to remember this concept. Thanks cano.