As the propeller turns, voids are formed on the trailing and leading edges of the propeller blades causing a loss of propulsive efficiency, pitting of the blades, and vibration. These voids are known as __________.

Correct Answer: Option A — cavitation

Cavitation occurs when propeller blade rotation creates localized low-pressure zones, causing water to vaporize. These collapsing vapor bubbles cause significant surface pitting, noise, and vibration, leading to a marked decrease in propulsive efficiency. This phenomenon is a critical consideration in marine engineering and vessel propulsion system maintenance.