Final answer:
The required visibility distance for parking on the highway to take on or let off passengers is not specified in the reference information. For a precise answer, one should consult local traffic laws.
Step-by-step explanation:
When taking passengers on or letting them off your vehicle on the highway, it is crucial to ensure safety by parking in a place that allows other drivers to see your vehicle with ample distance to adjust their driving accordingly. However, the specific distance required for visibility in front and behind the vehicle is not provided in the reference information given. In many regions, regulations may state that a certain minimum line-of-sight distance must be maintained, but without the exact legal code or guideline from a specific region, providing an accurate numerical answer is not possible. Therefore, I recommend checking local traffic laws for the correct figure. It is generally advised to stop in an area where your vehicle can be seen easily by others to allow for safe entry and exit of passengers, as well as to avoid impeding traffic flow and potentially causing accidents.