Choice "D" is correct. There is no requirement that the auditor's report on supplementary information required by GAAP be restricted.
Choice "c" is incorrect. An auditor is not required to audit required supplementary information, but the audit report should include an other-matter paragraph related to the supplementary information. When appropriate, this other-matter paragraph should state that the required supplementary information is included and the auditor has applied the required procedures.
Choice "a" is incorrect. An auditor is not required to reference other information in the financial statement audit report, but may choose to add an other-matter paragraph disclaiming an opinion on the other information.
Choice "b" is incorrect. When the auditor chooses to apply auditing procedures to the supplementary information, he or she may express an opinion regarding whether the supplementary information is fairly stated in all material respects in relation to the financial statements taken as a whole.