What must a driver do if a fire is noticed while driving?

When a driver notices a fire while driving, the most appropriate action is to stop in a safe location and assess the situation. This response is prudent for several reasons. First, safely pulling over allows the driver to remove themselves and any passengers from immediate danger. Secondly, assessing the situation can help determine the severity of the fire and the best course of action, such as whether to use an extinguisher or to evacuate the vehicle.

Continuing to drive, as suggested in one of the other options, could increase the risk of the fire spreading and endanger other road users. Simply alerting other drivers does not address the immediate danger posed to the vehicle occupants. While using a fire extinguisher can be appropriate in some scenarios, stopping safely and assessing the situation first is vital, as it allows the driver to decide if it's safe or necessary to attempt to fight the fire or evacuate the area entirely.