An internal auditor fails to discover an employee fraud during an assurance engagement. The nondiscovery is most likely to suggest a violation of internal auditing standards if it was the result of a A. Failure to perform a detailed review of all transactions in the area. B. Determination that any possible fraud in the area would not involve a material amount. C. Determination that the cost of extending procedures in the area would exceed the potential benefits. D. Presumption that the internal controls in the area were adequate and effective.