Answer:
D) Reduce the internal friction of the engine's parts.
Step-by-step explanation:
To increase the efficiency of the car's engine, an engineer most like has to reduce the friction within the internal engine parts. Reducing these friction reduces the useful energy lost as heat in these internal parts of the engine, when the engine parts do work against friction to move. In most everyday activities, engines and machines, energy is usually lost as heat due to frictional forces arising from two or more surfaces in contact.