When is it illegal to drive in the left lane of a highway?

Answer: B — When you are not passing another vehicle

It is illegal to drive in the left lane of a highway when you are not passing another vehicle because that lane is typically designated for faster-moving traffic and for overtaking slower vehicles. The left lane is intended to facilitate quicker travel and improve traffic flow. When drivers remain in the left lane without actively passing, it can create congestion and frustration for other motorists who wish to maintain higher speeds or pass those slower vehicles in the right lane. In many jurisdictions, including Ohio, traffic laws often specify that the left lane should primarily be used for passing, ensuring that all drivers can move efficiently without unnecessary delays. This rule helps maintain order on highways and encourages safe driving habits by keeping traffic moving smoothly.