Final answer:
The primary reason an auditor needs to understand a client's system of internal control over financial reporting is to assess risk and pinpoint areas with potential for misstatements in financial statements, guiding the audit process.
Step-by-step explanation:
The most important reason for an auditor to gain an understanding of an audit client’s system of internal control over financial reporting is to assess risk and identify areas where financial statement misstatements might be more likely.
An effective system of internal controls can provide a foundation for the safe operation of a company by establishing procedures and measures to prevent, or detect and correct, errors or fraud in the financial reporting process.
Thus, an auditor's in-depth understanding of these controls is critical to planning the audit because it helps the auditor decide where to focus the audit efforts and which areas may require more scrutiny.
Misstatements, whether due to error or fraud, could have a material effect on the financial statements and thus, understanding the internal controls helps the auditor to determine the nature, timing, and extent of auditing procedures to be performed.
Understandably, the option stating that the auditor gains this understanding to sell consulting services or that it is not a required part of the audit process are incorrect.
While recommendations to management may be a secondary benefit of understanding the internal controls, it is not the primary reason for an auditor's examination.