Which of the following statements describes why a properly designed and executed audit may not detect a material fraud?

(a.) Audit procedures that are effective for detecting an unintentional misstatement may be ineffective for an intentional misstatement that is concealed through collusion.

b. An audit is designed to provide reasonable assurance of detecting material errors, but there is no similar responsibility concerning material fraud.

c. The factors considered in assessing control risk indicated an increased risk of intentional misstatements, but only a low risk of unintentional errors in the financial statements.

d. The auditor did not consider factors influencing audit risk for account balances that have pervasive effects on the financial statements taken as a whole.