A driver holds only Category C1. The next job is a rigid goods vehicle with maximum authorised mass 12,500 kg and 3 passenger seats plus the driver. What is required?

1. C1 is enough, because passenger seats are under 8
2. C1 is enough, because 12,500 kg is under 18,000 kg
3. Category C is required, because 12,500 kg exceeds the 7,500 kg C1 cap
4. Category D is required because any extra seats change the class