Final answer:
The FASB requires changes in an accounting principle to be reported retrospectively, meaning the new principle is applied to all prior periods in the financial statements.
Step-by-step explanation:
According to the Financial Accounting Standards Board (FASB), the required approach for reporting changes in an accounting principle is B. Retrospectively. This means that when an accounting principle is changed, a company must apply the new principle to all prior periods presented in the financial statements, as if the new principle had always been used. This retrospective application is intended to enhance comparability and provide a consistent method for investors and other users of financial statements to assess financial performance over time.