Choice "A" is correct. The accountant's report on a review engagement should state that the accountant is not aware of any material modifications that should be made to the financial statements for them to conform with GAAP.
Choice "b" is incorrect. An accountant expresses limited assurance in a review engagement.
Choice "d" is incorrect. "Reasonable assurance about whether the financial statements are free of material misstatement" is required for audit engagements, but is not necessary for review engagements.
Choice "c" is incorrect. Examining evidence on a test basis is required for an audit engagement; procedures for a review engagement are limited to inquiry and analytical procedures.