i am confused where the "it" in c refers to

That every worker has a clean criminal record is of some importance to investment banks which is why a stringent background check is a necessary prerequisite for all of their job applicants.
a That every worker has a clean criminal record is of some importance to investment banks which is why a stringent background check is a necessary prerequisite for all of their job applicants
b Clean criminal records of their employees is important to investment banks; hence, a stringent background check are necessary prerequisites for employment
c Because they consider it important that all of their employees have a clean criminal record, investment banks require each job applicant to undergo a stringent background check
d It is of some importance that all investment banks’ workers have clean criminal records which is why many of them undergo stringent background checks
e The reason that investment banks require background checks of their applicants is because they require clean criminal records of their employees

answer is C) but what does the "it" in the question refer to? isnt that kind of unclear?