Final answer:
The concept that a driver should be able to stop within the distance that they can see in their headlights at night is related to 'nighttime visibility' and is a practice for safe driving after dark.
Step-by-step explanation:
In the context of driving, the rule that suggests you should always be able to stop within the distance you can see in your headlights is related to nighttime visibility. This is crucial for safe driving, as it ensures that you maintain a speed that allows you to react and stop in the case of an obstacle within the range of your headlights. However, this is not officially called the nighttime visibility rule, but it relates to the practice of safe driving at night. The question doesn't directly relate to the concepts listed in the SEO keywords provided, as they pertain to the physical limit of the human eye's ability to resolve points of light, such as car headlights from a distance, due to diffraction by the pupil.