Which of the Following Requires Recognition in the Auditor's Opinion

Which of the following requires recognition in the auditor's opinion as to consistency?

A) The correction of an error in the prior year's financial statements resulting from a mathematical mistake in capitalizing interest.
B) A change in the estimate of provisions for warranty costs.
C) The change from the cost method to the equity method of accounting for investments in common stock.
D) A change in depreciation method which has no effect on current year's financial statements but is certain to affect future years.