What action must drivers take when approaching an emergency vehicle responding to a call?

Answer: B — Immediately drive to the right and stop

When approaching an emergency vehicle responding to a call, drivers are required to immediately drive to the right and stop. This action is crucial for ensuring the safety of both the emergency responders and other road users. Emergency vehicles often need a clear path to quickly and effectively respond to incidents, and yielding by moving to the right allows them to pass safely without interruption. Additionally, stopping reduces the risk of accidents that could occur if drivers continue at their current speed or attempt to pass the emergency vehicle, which could create dangerous situations for everyone involved. This law helps facilitate efficient emergency response while maintaining safety on the roads. The other actions listed are inappropriate as they either impede the emergency vehicle's ability to respond quickly or do not adhere to traffic safety regulations designed for emergency situations.