A non-issuer uses a service organization whose services are part of the non-issuer's system of internal controls. In the integrated audit, how does an auditor evaluate whether the service auditor's report on controls provides sufficient appropriate evidence to support an opinion on internal controls over financial reporting?

A.By observing the service auditor to determine the level of knowledge about the entity under audit during the first week of the audit fieldwork.

B.By inquiring of the service auditor's reputation only from the company's outside attorney.

C.By assessing the results of the tests of controls and the service auditor's opinion on the operating effectiveness of the controls.

D.By performing a background check of the service auditor.