Which of the Following Best Describes the Primary Concern of the Audit

Which of the following best describes the primary concern of the audit manager upon review of engagement working papers of an auditor?

A) To ensure adequate control over the custody of working papers is exercised by the auditor.
B) To ensure that as part of the documentation the auditor collected original documents that can corroborate the audit findings.
C) To ensure that the work papers create background for subsequent reviews.
D) To ensure that the audit programs are followed by the auditor.