Under the Regulations on Road Passenger Transport and Passenger Terminals (the Provisions on Road Passenger Transport and Passenger Terminals (MOT Order 2020 No. 17, as amended)), what is the statutory restriction on carrying free child passengers (免票儿童) who do not occupy individual seats?

1. Free children can constitute up to 30% of the certified seating capacity
2. Free children are strictly prohibited on all Chinese roads under all circumstances
3. Children under 6 years (or under 1.2m) accompanied by adults may travel free without a seat, but the total number of free children must NOT exceed 10% of the coach's certified seating capacity
4. Each adult passenger may carry up to 3 free children without seats