Multiple pinholes develop near earlier copper repairs. What underlying mechanism should be evaluated before another spot repair?

Why A is correct

The best answer is: Evaluate the corrosion mechanism. Repeated failures may reflect water chemistry, velocity, electrical effects, workmanship, erosion, or uniform aging. Sampling, history, wall condition, and system layout distinguish a local defect from systemic risk. The transferred field condition applies the same plumbing design, installation, service, or safety principle to a different project setting. The alternatives omit a prerequisite, conflict with the approved method, or fail to control the stated sanitation or physical hazard.