Final answer:
The question is about the optical resolution limit of human eyes in Physics, relating to the maximum distance at which two headlights can be resolved.
Step-by-step explanation:
The question you've asked pertains to the subject of optics in Physics, specifically referring to the human eye's ability to resolve two separate sources of light at a distance.
The 'rule of thumb' mentioned is related to the resolution limits of the eye, which can be roughly estimated using such guidelines.
However, to accurately calculate the maximum distance at which the eye can resolve two headlights that are 1.3 meters apart, with a pupil diameter of 0.40 cm, more detailed optical formulas need to be applied that are grounded in the physical principles of diffraction and resolution.