Yes. More specifically, chances are minimal that an option would be incorrect because of incorrect idiomatic usage.
By the way, I find this interesting that you are getting most SC questions incorrect because of idiomatic usage. Interesting because GMAC opined that the usage of idioms offered an undue advantage to native English speakers (which you are:)).
p.s. p.s. Our book
EducationAisle Sentence Correction Nirvana discusses the
most prominently used and tested idioms, rather than presenting a laundry list of idioms to memorize. If you can PM you email-id, I can send you the corresponding section.