Answer:
The correct answer is letter "C": The change should be reported retroactively.
Explanation:
Changes in Accounting Principles happen when a company switches between various generally accepted accounting principles or adjusts the process by which a rule is applied. Those changes can take place in accounting mechanisms for Generally Accepted Accounting Principles (GAAP) or International Financial Reporting Standards (IFRS).
When the changes happen, companies must apply it retrospectively to all previous accounting periods, as if the norm would have been always there.