An auditor determined materiality for planning purposes before year$-$end based on a nonissuer entity's prior$-$year financial statements. During the audit, the auditor learns that the actual financial results are significantly different from those of the prior year because of a merger. The auditor's most appropriate response would be to:

A$.$

Revise materiality for the financial statements as a whole.

B$.$

Reassess the risk of material misstatement to determine whether detection risk remains appropriate.

C$.$

Reperform audit procedures completed before year$-$end.

D$.$

Reevaluate the sufficiency of audit procedures performed in the prior$-$year audit.