When must you not pass a vehicle on its left at an intersection?

For the question "Under what circumstances are you not allowed to overtake on the left at an intersection?" the correct answer is "3. When the vehicle in front is preparing to turn left."

The importance of this rule lies in its role in preventing collisions at intersections. If one vehicle is preparing to turn left while another attempts to overtake on the left, this can lead to a collision between the two vehicles. The turning vehicle may need to slow down or stop to wait for a safe opportunity to pass, so overtaking on the left increases the risk of an accident, especially in high-risk areas like intersections. By prohibiting overtaking in this situation, traffic flow and safety can be better maintained.