What must be checked in an inboard motor?

When inspecting an inboard motor, the essential components that need to be checked include the ballast and ballast tank. The ballast system is crucial for the stability and performance of a vessel, particularly in maintaining its center of gravity and improving handling during operation. Ensuring that the ballast tank is functioning properly is vital, as it can affect the vessel's ability to navigate safely and efficiently, especially in different water conditions.

The other components mentioned in the choices are important as well but relate more to the overall functionality and safety of the entire vessel rather than being specific to the inboard motor itself. For example, the bilge pump and water intake primarily deal with water management and drainage, while fuel lines and electrical systems concern the broader engine and operating systems of the boat. Propellers and steering cables are related to maneuvering the vessel, but do not directly pertain to the motor's operational integrity. Thus, the focus on balancing and stability inherent in the ballast and ballast tank makes it the correct aspect to check for an inboard motor.