What action should a defensive driver take if another driver honks their horn and yells an obscenity?

Answer: C — Nothing - continue driving safely and appropriately

A defensive driver’s primary focus is on maintaining safety and composure in potentially hazardous situations. When faced with another driver who is honking and yelling obscenities, the most prudent action is to continue driving safely and appropriately. This means keeping a cool head, avoiding escalation, and not succumbing to emotional reactions that can lead to aggressive driving or confrontational behavior. Retaliating verbally or with gestures only exacerbates the situation and can lead to dangerous driving behavior, potentially escalating into road rage. It's important to remember that aggressive responses can distract you from the task of driving and put everyone on the road at risk. While calling the police may seem like a reasonable response to threatening behavior, it is generally not necessary for simple instances of road rage or verbal insults unless the other driver poses an immediate threat to safety. Therefore, the optimal choice is to remain focused on safe driving, ignoring the provocations, and ensuring that your own actions do not contribute to the problem.