Choice "A" is correct. When the auditor concludes that an auditing procedure considered necessary at the time of the audit was omitted, the auditor should assess the importance of the procedure to the present ability to support the previously issued opinion. The results of other procedures that were applied may tend to compensate for the one omitted or make its omission less important.
Choice "c" is incorrect. If a procedure has been omitted, the auditor must consider whether other parties may be relying on the financial statements, even if the audit report had limited distribution.
Choice "d" is incorrect. The fact that the previous opinion was qualified does not negate the need to apply the omitted procedure.
Choice "b" is incorrect. Delays by client personnel may extend audit work, but do not provide a reason for omitting a procedure.