When is it permissible to drive in the left lane on a highway?

Driving in the left lane on a highway is primarily intended for passing other vehicles or preparing to turn left. This rule helps maintain a smooth flow of traffic and reduces the likelihood of accidents caused by slower vehicles obstructing faster-moving traffic.

The left lane is designed for overtaking slower vehicles in the right lanes, and when a driver uses it solely for these purposes, it promotes safety by allowing faster traffic to pass without unnecessary delays. Remaining in the left lane for other reasons can lead to congestion and frustrate drivers who wish to overtake, potentially causing dangerous situations.

Other options suggest scenarios that aren't consistent with safe driving practices. For instance, driving in the left lane when traffic is slow or when there are no vehicles behind you does not align with the intended use of that lane. The left lane should primarily serve the purpose of passing or preparing for a turn, in line with traffic laws.