Which of the following direct-reading gauges would most likely be used in the application of a pump suction pressure gauge?

Correct Answer: Option C — Compound gauge

A compound gauge measures both positive pressure and vacuum. Pump suction lines often experience vacuum during operation or positive pressure during priming or back-flushing. This dual-scale capability is essential for monitoring pump performance and identifying potential cavitation or suction side restrictions in accordance with standard marine machinery instrumentation practices.