Final answer:
The lobes on the camshaft are used to open each valve as the engine operates.
Step-by-step explanation:
The correct answer is C) Lobes. The lobes on the camshaft are specifically designed to open and close the valves as the engine operates. Each lobe corresponds to a specific valve, and as the camshaft rotates, the lobes press against the valve stems to open them. This allows the fuel-air mixture to enter the combustion chamber and the exhaust gases to exit.
For example, in a 4-stroke engine, the camshaft will have four lobes: one for the intake valve, one for the exhaust valve, and two for the other two valves. The shape and size of the lobes determine the timing and duration of the valve opening and closing events.