In a high-pressure starting-air compressor system, why is compression performed in two or more stages rather than a single stage?

1. A. Single-stage compression cannot produce sufficient pressure to open the air-start valves against cylinder pressure
2. ✓ Single-stage compression to high pressure generates excessive heat, so intercoolers between stages remove that heat and condense moistureCorrect
3. C. Multi-stage compression is required to prevent oil carryover from reaching the starting-air manifold flame arrestors
4. D. A single-stage compressor cannot be fitted with a relief valve, creating an overpressure hazard