Question

The _______ optimizes airflow, keeps cylinder pressure in a certain range, and determines the engine's operating range.

Answer 1

I think it would be A) valve lift
Sorry if I'm wrong

Answer 2

The answer is: D. Valve timing

Valve timing refers to the exact timing when the piston engine is being either opened or closed. The closing and opening of the piston engine  regulates the cylinder filling process. Which means that by setting the valve timing correctly, we can optimize the amount of airflow that got into the machine and keeps the engine from overheating.