When is it mandatory to use turn signals?

Using turn signals is mandatory when a driver is either turning or changing lanes. This practice serves a critical purpose in road safety by providing clear communication to other road users about your intentions. Signaling when turning informs other drivers, cyclists, and pedestrians that you are changing the direction of your vehicle, allowing them to anticipate your movements and react accordingly.

Moreover, when changing lanes, signaling is essential to prevent accidents. It alerts drivers in adjacent lanes or behind you that you are merging into their lane, creating a safer driving environment. Failing to signal can lead to confusion, risky situations, and potentially collisions, as other drivers may not be aware of your intended actions.

The other choices do not encompass the full requirement of using turn signals. For example, only signaling for lane changes overlooks situations when turning at intersections, which is also crucial for safety. Similarly, limiting signal use to residential areas or adverse weather conditions misses the broader requirement for all driving scenarios, as the need for clear communication exists regardless of location or weather.