Leaving a retarder on when the road is wet or icy helps prevent the drive wheels from skidding.
Correct answer: B – FALSE
A retarder does not protect against skidding on a slippery surface. Because its braking force acts on the drive wheels, poor traction can cause those wheels to skid. Turn the retarder off when the roadway is wet, icy, or covered with snow, and adjust speed and braking to the available traction.
Source: Georgia Commercial Driver’s Study Guide — § 2.3.4, “Retarders”

