Which of the Following Statements Best Describes the Auditor's Responsibility

Which of the following statements best describes the auditor's responsibility regarding the detection of fraud?

A) The auditor is responsible for the failure to detect fraud only when such failure clearly results from non-performance of audit procedures specifically described in the engagement letter.
B) The auditor must extend auditing procedures to actively search for evidence of fraud in all situations.
C) The auditor should design auditing procedures to provide reasonable assurance that fraud material to the financial report is detected.
D) The auditor is responsible for the failure to detect fraud only when an unmodified opinion is issued.