What is a traffic offence related to lane usage?

Driving on the left lane without reason constitutes a traffic offence related to lane usage because the left lane on a multi-lane roadway is usually designated for overtaking slower vehicles. In many countries, including Belgium, regulations mandate that drivers should stay in the right lane when not actively passing another vehicle. This rule is in place to promote smoother traffic flow and enhance safety. Occupying the left lane unnecessarily can lead to congestion and impede the progress of faster-moving vehicles that are attempting to overtake.

The other options, while they may involve driving practices that have implications for safety and legality, do not specifically pertain to lane usage. For example, driving too slowly can be an issue but is more about speed regulation rather than lane placement. Not using indicators relates to signaling and communication with other road users, and stopping at a green light is generally an infraction concerning the adherence to traffic signals rather than improper lane usage.