Choice "C" is correct. If the financial statements, including accompanying notes, fail to disclose information that is required by generally accepted accounting principles, the auditor should express a qualified or adverse opinion, depending on pervasiveness.
Choice "b" is incorrect. disclaimer of opinion is not an appropriate report for inadequate disclosure or a GAAP departure.
Choice "d" is incorrect. A disclaimer of opinion or an unmodified opinion with an emphasis-of-matter paragraph are not appropriate for a client with a material undisclosed item or GAAP departure.
Choice "a" is incorrect. An unmodified opinion with an other-matter paragraph is not appropriate for a client with a material undisclosed item or GAAP departure.