What should drivers do when an emergency vehicle with flashing lights is parked along the roadway?

Answer: D — Both a and b are correct

When an emergency vehicle with flashing lights is parked alongside the roadway, it is essential for drivers to take specific actions to ensure the safety of everyone involved. Slowing down and passing carefully is crucial because it helps reduce the risk of an accident while navigating around the emergency vehicle. This allows drivers to maintain control of their vehicle in potentially hazardous conditions. Additionally, moving over if safe is also an important step. If there is enough space in the adjacent lane, shifting over can provide additional protection for emergency personnel who may be working nearby. This practice helps create a buffer zone, minimizing the likelihood of collisions. Combining both actions—slowing down and moving over when it's safe—exemplifies responsible driving behavior in the presence of emergency vehicles, emphasizing the need for caution and consideration.