What safety procedure should be performed before starting the engine?

Before starting the engine, checking for fuel leaks is essential for ensuring safety on the water. Fuel leaks can lead to dangerous situations, including fire hazards and environmental contamination. By inspecting the fuel system for any signs of leakage, boat operators can prevent potential accidents or emergencies that could arise once the engine is running. Ensuring the integrity of the fuel system is a critical step in the overall safety protocol for operating a vessel.

In the context of the other choices, while inspecting the propeller is important for safe operation, it specifically pertains to performance rather than immediate safety concerns. Reviewing boating regulations is essential for legal compliance and understanding operational guidelines but does not directly address the immediate risk posed by the engine starting with potential fuel leaks. Ensuring all passengers are seated is also crucial for safety, especially during operation, but it does not address the risks associated with the engine or fuel system prior to starting the engine.