Which of the following would most likely cause an internal auditor to consider adding fraud...

Improper segregation of duties is a fundamental control weakness that significantly increases the risk of fraud. When one individual has control over multiple stages of a financial transaction or operational process, it creates opportunities for fraudulent activities to occur and remain undetected. While incentives and bonus programs (Option B), employee concerns (Option C), and lack of an ethics policy (Option D) are also important indicators of potential fraud risk, they do not present as direct and immediate a vulnerability as improper segregation of duties.References:

IIA Practice Guide on Fraud Prevention and Detection in an Automated World.

IIA Standard 2120: Risk Management.