Under Article 55 of the Road Traffic Safety Law Implementation Regulations, what is the statutory passenger rule for light motorcycles / mopeds (轻便摩托车 - Class F)?

1. One passenger under 18 years old is permitted
2. One adult passenger is permitted if wearing protective gear
3. Two passengers are permitted if both wear helmets
4. Light motorcycles / mopeds are strictly prohibited from carrying any passengers (轻便摩托车不得载人)