In Assessing Internal Controls the Auditor Is Suppose to Apply

In assessing internal controls the auditor is suppose to apply the concept of reasonable assurance,which indicates that

A) there should be a clear separation of duties between personnel who authorize,record,and hold assets.
B) the costs of a control should not exceed its benefits.
C) testing of the controls should provide assurance that they work most of the time.
D) testing of the controls should provide reasonable assurance that they are working properly.