Final answer:
The most reliable evidence for an auditor comes from a combination of more effective internal controls and more effective external controls, as they work together to ensure the accuracy and integrity of financial statements.
Step-by-step explanation:
The question aims to identify which combination of internal and external controls provides the most reliable evidence for an auditor. When it comes to auditing, internal controls are the processes and procedures put in place by a company to ensure the integrity of financial and accounting information, promote accountability, and prevent fraud. External controls, on the other hand, refer to the regulations and requirements imposed by external entities.
Among the options given, the pairing of more effective internal control with more effective external control would give the most reliable evidence because both are operating at optimal levels, thereby reinforcing each other and minimizing the risk of errors and misstatements. A system of effective internal controls reduces the likelihood of inaccuracies within the company's financial statements, and when paired with stringent external controls, it enhances the trustworthiness of the financial information verified by the auditor.