The correct answer is D. Procurement fraud prevention requires ongoing vendor monitoring based on the organization's highest-risk vendor schemes. Monitoring should focus on practical red flags, such as unusual pricing, duplicate vendors, related-party indicators, excessive change orders, suspicious payment patterns, or vendors lacking proper support. Option A violates segregation of duties because the person maintaining the vendor master file should not also approve invoice payments. Option B is weak because vendor background checks should occur before vendors are added to the master file, not after. Option C is incorrect because procurement monitoring should be ongoing and risk-based, not restricted to annual reviews. The ACFE material emphasizes vendor management, vendor master file controls, and monitoring based on relevant red flags.

================