Choice "D" is correct. If one or more of the significant assumptions do not provide a reasonable basis for the financial statements, an adverse opinion would be issued.
Choice "b" is incorrect. A pro forma financial statement is one that shows historical financial statements as they would have been if a hypothetical event had occurred. The term "pro forma opinion" is not used.
Choice "a" is incorrect. A qualified opinion might be issued if AICPA presentation guidelines were not followed, but when the basis for the financial statements is not reasonable, only an adverse opinion is acceptable.
Choice "c" is incorrect. If one or more of the significant assumptions do not provide a reasonable basis for the financial statements, an adverse opinion would be issued. An unmodified opinion with an explanatory paragraph would not be sufficient.