Gasoline fueled engines require ignition protection ratings on all of the following, EXCEPT:

Gasoline fueled engines necessitate ignition protection to prevent sparks or heat from igniting flammable vapors in the engine compartment. Components like ignition distributors, starters, and alternators can generate sparks or heat during operation, which can potentially ignite gasoline vapors. Therefore, these parts must meet specific ignition protection ratings to ensure safety and compliance with standards.

On the other hand, spark plugs are designed to ignite the air-fuel mixture in the engine cylinder, but they are located inside the engine itself, away from the fuel vapors present in the engine compartment. Spark plugs are part of the combustion process and do not require the same level of ignition protection because they are not exposed to the same risks as the other components outside of the engine's sealed environment. This context highlights why the correct answer is that spark plugs do not require ignition protection ratings, as their operation does not pose a risk of igniting external gasoline vapors.