A single audit, conducted under the provisions of 2 CFR Part 200 (Uniform Guidance), includes an audit of the entity's financial statements. The resulting auditor's report must express an opinion on whether these financial statements are presented fairly, in all material respects, in accordance with the applicable financial reporting framework. Generally Accepted Accounting Principles (GAAP) is the standard framework for U.S. entities. While governmental entities follow standards from the Governmental Accounting Standards Board (GASB) and non-profits follow the Financial Accounting Standards Board (FASB), both fall under the umbrella of GAAP. Therefore, GAAP is the most comprehensive and accurate answer.

A: Auditors provide reasonable assurance against material misstatement from fraud, not an absolute opinion that the financial statements are entirely "free from fraud."

C: This is too specific. Single audits also apply to not-for-profit organizations, which follow FASB standards, not GASB. GAAP encompasses both.

D: The Government Accountability Office (GAO) issues auditing standards (the Yellow Book), not the accounting principles used for preparing financial statements.

1. U.S. Office of Management and Budget (OMB). (2014). 2 CFR Part 200 - Uniform Administrative Requirements, Cost Principles, and Audit Requirements for Federal Awards. In §200.515, "Audit reporting," paragraph (a) explicitly states, "The auditor's report must... include an opinion (or disclaimer of opinion) as to whether the financial statements are presented fairly in all material respects in accordance with generally accepted accounting principles..."

2. U.S. Government Accountability Office (GAO). (2018). Government Auditing Standards (GAO-18-568G). Chapter 4, "Standards for Financial Audits," paragraph 4.16, states, "The report on the financial statements provides the auditor’s opinion or disclaimer of opinion on whether the financial statements are presented fairly in all material respects in conformity with the applicable financial reporting framework." The document consistently refers to GAAP as the primary example of such a framework for U.S. entities.