What should a driver check after a long trip to ensure safety?

After a long trip, a driver should check the condition of all lights and signals to ensure safety. This is crucial because functioning lights and signals are essential for visibility and communication with other drivers on the road. Inadequate or malfunctioning lights, such as headlights, taillights, and turn signals, can significantly increase the risk of accidents, especially in low-light conditions or adverse weather. Ensuring that all lights and signals are operational helps maintain not only the driver's safety but also the safety of others on the road.

The other options, while relevant in various contexts, do not address the immediate safety needs as effectively. For instance, checking the baseline fuel level is important for fuel management but does not directly impact safety. Similarly, evaluating the driver's comfort level, while relevant to driver fatigue and overall performance, does not address potential mechanical or visibility issues. Finally, while it is important to know how many tires are remaining and in good condition, this option does not encompass the critical need for proper functioning lights and signals to share intentions with other road users effectively.