Final answer:
An air compressor should typically stop pumping before it reaches 120 psi. However, the compressor should always be operated as per the manufacturer's specifications, which could vary from this value.
Step-by-step explanation:
The pressure up to which an air compressor should pump depends entirely on its design and intended purpose. However, comprehensively speaking, as a safety measure, it's commonly recommended that an air compressor should stop pumping before it reaches a pressure threshold of 120 psi (option c). This is critical to avoid potential damage to the compressor or connected equipment that can be caused by an overpressure condition.
Remember that the compressor should always be operated as per the specifications from the manufacturer, which may differ from the value provided here. Always stick to the safety range recommended by the manufacturer when operating an air compressor to prevent any mishaps.
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