Which standard is applicable to Single Audits?

Single Audits involve the examination of a government entity's financial statements and compliance with federal regulations and laws. The correct answer includes all three standards because they each play a role in the Single Audit process.

GAAS, or Generally Accepted Auditing Standards, provides a foundation for the audit, ensuring that the auditor's performance meets certain professionalism and quality criteria. GAGAS, known as Generally Accepted Government Auditing Standards, offers additional requirements specific to government auditing to address the unique responsibilities and risks associated with public funds.

The Office of Management and Budget Circular A-133 (now superseded by the Uniform Guidance in 2 CFR Part 200, Subpart F) established guidelines for Single Audits of federal award recipients, emphasizing compliance with the federal laws and regulations.

Thus, all these standards work together in the framework of a Single Audit, making the correct answer a comprehensive inclusion of all the standards mentioned. This reflects the multi-faceted approach needed to ensure effective auditing in government contexts.