When is it necessary to use turn signals?

Using turn signals is essential for safe driving, as they communicate your intentions to other road users. The correct answer reflects the requirement to signal both when turning and when changing lanes. This practice helps prevent accidents by providing clear information to drivers, cyclists, and pedestrians about your movements.

In situations where you're making a turn at an intersection, signaling informs others that you're about to change your direction. Similarly, when changing lanes on the highway or road, a turn signal alerts nearby drivers of your intention to shift your position. This transparency promotes safer interactions on the road and helps to anticipate the actions of others.

The other options are limited in scope, suggesting that signaling is only necessary in very specific circumstances or only when being observed by law enforcement, which does not enhance overall roadway safety. Proper signal use should be a consistent habit for all drivers in any driving condition.