Question

when should you use \plugging\ to stop the lift truck?
when you leave the lift truck on a ramp or incline.
when you want to stop smoothly and gradually.
whenever you stop the lift truck.
when you want to stop quickly.

Explanation:

Plugging is a method used to stop a lift truck quickly. It is not for smooth or gradual stops (as that would be normal braking). Leaving on a ramp or incline requires chocking wheels, not just plugging. And plugging isn't for every stop (normal stops are different).

Answer:

When you want to stop quickly.