Choice "D" is correct, a "change in accounting estimate" affects only the current and subsequent (future) periods, if the change affects both. It does not affect "prior periods," nor "retained earnings."
Choice "b" is incorrect. Restating prior years' financial statements is required when comparative financial statements are shown for prior period adjustments of "corrections of errors," "changes in entities," and changes in accounting principle.
Choices "c" and "a" are incorrect. A "change in accounting estimate" does not affect prior periods.
