Final answer:
In heavy fog, drivers should slow down and use low beam headlights to improve visibility. Following too closely or using bright lights can increase the risk of accidents.
Step-by-step explanation:
When driving through heavy fog, the correct action to take is to slow down. This increases the time available to react to road conditions and obstacles that may be difficult to see.
Turning on bright lights is not advisable because they reflect off the fog and can worsen visibility. Instead, drivers should use their low beam headlights. It is also unsafe to follow the car in front of you closely due to reduced visibility, which increases the chances of a collision. Using parking lights only is inadequate because they are not as visible as headlights. Additionally, noticing changes in your headlights or other lights, such as a dimming when other electrical devices are used, may indicate additional resistance or electrical load in the vehicle’s system, which is normal but should be monitored for significant changes.