Final answer:
The auditor should inform senior management and the audit committee of the findings and discuss possible further investigation, ensuring proper adherence to company policy and legal requirements. Thus, the option 1 is the correct answer.
Step-by-step explanation:
When an auditor uncovers a plan to overstate inventory which would inflate profits, the correct course of action is to inform senior management and the audit committee of the findings and discuss possible further investigation. This is because senior management and the audit committee have the responsibility and authority to address and rectify such significant issues. Reporting the matter transparently helps to maintain the integrity of the financial reporting process and ensures that any actions taken are legitimate and in accordance with company policy and legal requirements. It would be inappropriate to inform the divisional manager of the suspicions prior to reporting, as they may be involved in the fraudulent activity. Conducting interviews with subordinates for a definite case or reporting suspicions to the external auditor should come after alerting the company's senior management and audit committee.