At an unregulated crossroads of equal roads, three vehicles arrive and all intend to go straight: vehicle A is travelling southbound (it came from the north), vehicle B is travelling westbound (it came from the east), and vehicle C is travelling northbound (it came from the south). Nothing approaches from the west. In what order do they pass?

1. A, then B, then C — A is the only driver with no vehicle approaching from its own right.
2. B, then C, then A — B entered the junction from the east side.
3. C, then B, then A — the northbound vehicle always clears the junction first.
4. They pass in order of arrival, because the right-hand rule cannot resolve three vehicles.