Which of the listed classes of electrical insulation is suited for the highest operating temperature?

Correct Answer: Option D — Class 180 (H)

Insulation classes are defined by their maximum allowable operating temperatures. Class 180 (H) is rated for 180°C, significantly higher than Class A (105°C) or Class B (130°C). This high-temperature capability is critical for marine motors operating in confined, high-ambient engine room environments where thermal stress is a constant factor.