Which of the following compressors on a motor ship would most likely operate at approximately 100 psig?

Correct Answer: Option D — Ship's service air compressor

Ship's service air systems typically operate at 100-125 psig to support pneumatic tools, controls, and general utility requirements. Starting air compressors operate at much higher pressures (often 250-450 psig) to meet main engine starting requirements, while emergency compressors are generally smaller units designed for specific, limited-capacity backup functions.