Detective controls are designed to identify and detect errors or fraud after they have occurred. Receipts for employee expenses serve as a detective control by providing evidence of transactions, enabling verification and review of expenses to identify any fraudulent or unauthorized activities. Awareness of prior incidents of fraud (Option A) is more of a preventive control, contractor non-disclosure agreements (Option B) are preventive controls to mitigate risks of information leakage, and verification of currency exchange rates (Option C) is more of a transaction control. References: IIA Glossary – Detective Controls, COSO Framework