Choice "D" is correct. GAAP allows a company to use different methods for costing different inventories as long as the methods are disclosed. Thus, the audit report would be unmodified; there is no departure from GAAP.
Choice "b" is incorrect. The consistency standard refers to changes in application of accounting practices between periods, affecting the comparability of financial statements. There is no indication Digit made any change in methods.
Choice "c" is incorrect. Use of different methods for costing inventory is permissible under GAAP, and would not result in a qualification of the auditor's report.
Choice "a" is incorrect. Use of different methods for costing inventory is permissible under GAAP, and would not result in an adverse report.