Choice "D" is correct. The auditor's risk assessment affects the nature, extent, and timing of audit procedures, but does not determine the relevance of audit evidence.
Choice "a" is incorrect. The relevance of audit evidence depends in part on whether the audit procedure is designed to directly test an assertion. If the audit procedures is designed to directly test an assertion and the evidence doesn't tell us anything about that assertion, then the evidence would not be relevant.
Choice "c" is incorrect. The relevance of audit evidence depends in part on whether the audit procedure is designed to test for an understatement or overstatement.
Choice "b" is incorrect. The relevance of audit evidence depends in part on the timing of the audit procedure.