Will be stiffer to better retract the valves.

• A. Rocker arm
• B. Valve spring
• C. Hydraulic lifter
• D. Bucket lifter

Answer: (B)

The key idea is that the valve spring provides the restoring force that pulls the valve back toward the closed position after it’s opened. Making this spring stiffer increases the closing force, helping the valve retract (close) more quickly and reliably, especially at higher engine speeds. If the spring is too soft, the valve can fail to close fully or even float at high RPM, leading to timing and sealing problems. The other components—rocker arm, hydraulic lifter, and bucket lifter—don’t provide the primary closing force; they mainly transmit motion or adjust clearance, so they don’t control how actively the valve retracts.