Final answer:
The basic speed rule instructs drivers to operate their vehicles at a speed that is safe and reasonable for existing and potential conditions, taking into account factors such as road, traffic, visibility, and weather.
Step-by-step explanation:
The answer to the question Basic speed rule: always drive at a speed that is ___ and ____ for the existing and P___ conditions is: always drive at a speed that is safe and reasonable for the existing and Potential conditions. This rule emphasizes the importance of adapting your driving speed not just to the speed limit, but to the current road, traffic, visibility, and weather conditions. When the conditions are poor, you should reduce your speed, even if that means driving below the posted speed limit.
For example, in heavy rain or fog, it would be safer to drive at a speed lower than the posted limit. Similarly, if you are driving through a congested city area with lots of pedestrian activity, it's wise to adjust your speed accordingly, even if other drivers around you are exceeding the speed limit.
The situation described with Peter encountering a driver going below the speed limit illustrates the importance of understanding that there are potential hazards – such as elderly drivers or others who may be more cautious – and adjusting your driving speed is not only a legal responsibility but also a question of safety and courtesy.