Which of the following best defines an audit?

An audit is best defined as a systematic examination of records to ascertain their accuracy. This definition captures the essence of what an audit entails: a structured and methodical approach to reviewing and evaluating financial records, processes, and control mechanisms within an organization. The thoroughness of this examination is crucial, as it is typically carried out by trained professionals who follow established auditing standards and procedures. This systematic approach ensures that the auditor can provide a reliable opinion regarding the truthfulness of the financial statements and compliance with relevant regulations.

In contrast, the other options do not accurately reflect the comprehensive nature of an audit. An informal review of financial statements does not convey the rigorous processes and standards that characterize a formal audit. A spontaneous check of compliance implies a lack of preparation and systematic review, which are essential components of a proper audit. Lastly, a subjective assessment of organizational performance suggests a reliance on personal judgment rather than the objective, factual examination required in auditing, which is based on evidence and standards rather than subjective interpretation. Thus, the chosen definition aligns perfectly with established auditing practices and principles.