Choice "D" is correct. The FASB Accounting Standards Codification is the single source of authoritative nongovernmental U.S. GAAP.
Choice "b" is incorrect. The International Financial Reporting Standards are not an authoritative source of U.S. GAAP.
Choice "a" is incorrect. FASB Statements of Financial Accounting Standards are included in the Accounting Standards Codification.
Choice "c" is incorrect. Per the FASB, the Statements of Financial Accounting Concepts are not GAAP.
