The same building-drain location blocks every few months. What should follow temporary restoration of flow?
- AReduce every fixture flow
- BUse progressively stronger acid
- CSchedule endless routine cabling for the described plumbing system and documented site conditions
- Inspect and locate the underlying defect before choosing repair
Why D is correct
The best answer is: Inspect and locate the underlying defect before choosing repair. Repeated blockage can result from offset joints, roots, belly, damage, grease, or improper grade. Camera inspection, locating, records, and flow evidence support a targeted repair instead of repeated symptoms treatment. 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.