A driver on a priority road approaches an intersection where another vehicle is emerging from a side road but a police officer gives a stop signal to the priority road. What should the driver do?

1. Obey the police officer and stop, even though the driver is on the priority road
2. Ignore the officer because priority-road signs always rank higher
3. Accelerate because the side-road vehicle must yield
4. Stop only if the side-road driver waves