Under which of the following circumstances would a disclaimer of opinion be appropriate?
a. The auditor is engaged after fiscal year-end and is unable to observe physical inventories or apply alternative procedures to verify their balances.
b. The auditor is unable to determine the amounts associated with illegal acts committed by the client's management. c. The financial statements fail to contain adequate disclosure concerning related party transactions.
d. The client refuses to permit its attorney to furnish information requested in a letter of audit inquiry.