A camshaft may directly control the operation of which components?

The camshaft plays a critical role in the operation of an internal combustion engine by controlling the timing and movement of the engine's valves. Both intake valves and exhaust valves are directly controlled by the camshaft through a system of cam lobes that push against valve lifters, which in turn open and close the valves at precise intervals to allow fuel and air into the combustion chamber and exhaust gases out.

In addition to the valves, certain engine designs may have unit type injectors that are also influenced by the camshaft. For instance, in some diesel engines, the camshaft can control the injection timing by operating the injectors directly, ensuring that fuel is injected into the combustion chamber at the optimal moment for efficient combustion.

Thus, considering that the camshaft is involved in the operation of both intake and exhaust valves, as well as potentially controlling unit type injectors in certain engines, the correct answer encompasses all of these components. This broad function highlights the camshaft's importance in engine performance and efficiency across different types of engines.