Under which of the following circumstances would an auditor's expression of an unmodified opinion be inappropriate? A. The auditor is unable to obtain the audited financial statements of a significant subsidiary. B. The financial statements are prepared on the entity's income tax basis. C. There are significant deficiencies in the design and operation of the entity's internal control. D. Analytical procedures indicate that many year-end account balances are not comparable with the prior year's balances.