Which hand-and-arm signal indicates that a driver is slowing or stopping?

The hand-and-arm signal for a driver indicating that they are slowing down or stopping is represented by the arm being extended straight out and downward. This specific position is universally recognized among drivers and serves as a clear signal to other road users, including those behind the vehicle, about the driver's intent to reduce speed or come to a stop.

Using this signal is particularly important for ensuring safety on the road, as it communicates the driver's actions to those who may not have a clear view of the vehicle's brake lights, especially in situations where visibility might be obstructed.

The other options represent different actions: an arm straight out typically signifies a left turn, while an arm raised upward is a signal for a right turn. Not using any signals can lead to confusion and increase the risk of accidents, as it provides no information to other drivers regarding the vehicle's intended maneuvers. Thus, the correct signal for slowing or stopping is the arm extended and pointing downwards.