What should a driver do before passing another vehicle?

Answer: B — Ensure adequate clearance

Before passing another vehicle, ensuring adequate clearance is essential for a safe maneuver. This involves assessing the space available between the vehicle being passed and oncoming traffic, as well as the distance needed to avoid merging back into the lane too soon after passing. Adequate clearance helps prevent accidents and allows for a smooth transition back into the original lane. Proper clearance not only considers the physical distance required to maneuver safely but also accounts for the speed of both vehicles. A driver must ensure that there is enough room to safely complete the pass without encroaching into the path of the oncoming vehicle or the vehicle being passed. This consideration is crucial in maintaining safety for everyone on the road. While increasing speed, making eye contact with the other driver, or honking the horn may appear to be helpful actions, they do not directly address the fundamental need for maintaining safe spatial distance while executing a pass. Therefore, ensuring adequate clearance is the most critical factor in this scenario.