For which of these flashing lights should you pull over?

Answer: D — Flashing red and blue

Flashing yellow lights indicate caution or a warning to proceed with care. Flashing green lights indicate that the vehicle has the right-of-way and can proceed. Flashing red lights indicate the driver must stop and yield to other drivers before proceeding. Flashing red and blue lights indicate an emergency vehicle, such as a police car, and require all other drivers to pull over and yield the right-of-way. This is important for the safety of the emergency responders as well as other drivers on the road. Therefore, the correct answer is flashing red and blue lights.