What is the requirement for returning to your lane after passing another vehicle?

Answer: B — Before 100 feet of an oncoming vehicle

The requirement for returning to your lane after passing another vehicle is to ensure safety and avoid collisions. The correct answer emphasizes the need to return to your lane before 100 feet of encountering an oncoming vehicle. This distance is critical as it provides enough space to merge back into the lane safely without interfering with the oncoming traffic. Returning to your lane too late can increase the risk of accidents, as the oncoming vehicle may not have sufficient time to react. Thus, returning to your lane before reaching the 100-foot mark is a vital safety measure that helps maintain clear sight lines and safe distances between vehicles. The other choices present distances that either exceed this safety threshold or pertain to contexts not directly associated with the immediate actions of merging after passing.