Which mandatory oversight procedure is utilized to detect and prevent improper purchases in the program?

The correct choice highlights the importance of Daily Data Mining (DM) Case Reviews as a crucial oversight mechanism within the DoD Governmentwide Commercial Purchase Card (GPC) program. This procedure is designed to continuously monitor purchasing activities by analyzing transaction data on a regular basis.

Daily Data Mining Case Reviews help in proactively identifying irregularities or patterns that may indicate improper purchases. By doing so, the program can take immediate corrective actions, ensuring compliance with established purchasing regulations and guidelines. This daily scrutiny allows for swift intervention before problematic purchases can escalate, promoting a culture of accountability and transparency within the program.

While other choices such as Monthly Compliance Audits, Annual Program Review, and Ad-hoc Purchase Investigations have their individual significance in the broader oversight framework, they do not match the immediacy and frequency of Daily Data Mining. Monthly and annual reviews are periodic and thus may not capture issues as quickly as daily monitoring, while ad-hoc investigations occur in response to specific concerns rather than being a consistent preventive measure. Therefore, the structured and systematic approach of Daily Data Mining sets it apart as the optimal method for preventing and identifying improper purchases in the GPC program.