Final answer:
The correct answer is D) spring. The spring closes the valve in a cylinder head. The rocker arm is connected to the valve by a pushrod. When the valve is open, the spring is compressed. When the camshaft rotates to close the valve, the spring expands and forces the valve shut.
Step-by-step explanation:
The correct answer is D) spring. The spring is responsible for closing the valve in a cylinder head. When the camshaft rotates, it pushes down on the lifter, which then pushes down on the rocker arm. The rocker arm is connected to the valve by a pushrod. When the valve is open, the spring is compressed. When the camshaft rotates to close the valve, the spring expands and forces the valve shut.
The spring is responsible for closing the valve in a cylinder head. When the camshaft rotates, it pushes down on the lifter, which then pushes down on the rocker arm. The rocker arm is connected to the valve by a pushrod. When the valve is open, the spring is compressed. When the camshaft rotates to close the valve, the spring expands and forces the valve shut.