What type of primer is used in the pump?

The correct choice identifies the type of primer commonly used in fire pump systems, which is a Waterous, no oil primer. This type of primer uses a rotary vane mechanism and operates on a 12-volt electric system. Using an electric rotary vane primer is preferable in fire rescue operations due to its efficiency in creating a vacuum to facilitate the quick priming of the pump, which is critical during emergency response situations.

Using a no oil primer helps to prevent contamination of the water supply and ensures that the system remains clean. This is particularly important in firefighting scenarios where water is being pumped to extinguish fires, as any contamination can pose health risks. The 12-volt system is advantageous as it can be powered by the vehicle's electrical system, ensuring reliability and readiness when needed.

In comparison, the other options present different types of primers that do not align with the specifications and requirements established in standard firefighting operations. An air-powered, oil-based manual pump may not provide the efficiency or reliability needed. Likewise, a pneumatic primer or a gas-powered primer may lack the necessary speed and ease of use required for prompt response in emergencies.