Choice "A" is correct. The auditor should issue an "unmodified opinion" when management adequately discloses future events, the outcome of which are not susceptible of reasonable estimation. Under U.S. auditing standards an emphasis-of-matter paragraph may be added by the auditor if the matter is of such importance that it is fundamental to the users' understanding of the financial statements. International Standards on Auditing recommend the addition of a paragraph describing the significant uncertainty.
Choice "b" is incorrect. "Subject to" qualified opinions are not permitted.
Choice "d" is incorrect. An "except for" qualified opinion would not be used as there is adequate disclosure and there are no scope limitations.
Choice "c" is incorrect. An adverse opinion would not be used because the FS are presented "fairly" in conformity with GAAP.