Final answer:
Additives known as Detergents are used to reduce carbon deposits in engines, maintaining cleanliness and efficiency.
Step-by-step explanation:
The additive responsible for reducing carbon deposits on engine components such as piston rings and valves is Detergents. Unlike other additives mentioned, detergents help to clean the engine by preventing deposits from forming on internal parts. Detergents keep the engine running cleanly and efficiently, thereby maintaining proper performance and reducing the risk of engine knock or damage. Antioxidants are used to prevent the oxidation of the fuel, while octane boosters are typically used to increase the fuel's octane rating and prevent knocking. Friction modifiers are added to reduce the friction between moving parts but do not contribute to the cleanliness of the engine's internals.