Internal audit observed an increase in defects of newly installed spare parts.

The most effective way to mitigate the risk of poor-quality spare parts is through independent verification of deliveries, such as inspections and testing. This detects defects before acceptance and payment, reducing the likelihood of defective parts entering operations.

Option A adds approval steps but does not address product quality. Option B relies on vendor statements, which may be unreliable. Option D strengthens contract language but does not ensure compliance at delivery.