Choice "A" is correct. Audit documentation should show that the accounting records agree or reconcile with the financial statements.
Choice "d" is incorrect. Audit documentation may be permitted to serve as a reference source for the client.
Choice "c" is incorrect. Audit documentation may contain critical comments concerning management (e.g., documentation of disagreement with the opinions of management, such as accounts receivable valuation).
Choice "b" is incorrect. Audit documentation is not the support for the FS. The client's books and records are the support for the FS. Audit documentation should be the principal support for the work the auditor has done to support the opinion provided on the auditor's report.