Monel metal is an alloy composed mainly of __________.

Correct Answer: Option A — nickel and copper

Monel is a high-strength, corrosion-resistant nickel-copper alloy, typically containing approximately 67% nickel and 30% copper. Its superior resistance to seawater and steam makes it a standard material for marine pump shafts, valve trim, and fasteners, as specified in maritime engineering standards for corrosive environments.