According to IIA Guidance, Which of the Following Is Least

According to IIA guidance, which of the following is least likely to be a key financial control in an organization's accounts payable process?

A) Require the approval of additions and changes to the vendor master listing, where the inherent risk of false vendors is high.
B) Monitor amounts paid each period and compare them to the budget to identify potential issues.
C) Compare employee addresses to vendor addresses to identify potential employee fraud.
D) Monitor customer quality complaints compared to the prior period to identify vendor issues.