Under the PRC Law on the Protection of Persons with Disabilities and taxi service standards, how must a taxi driver handle a visually impaired passenger accompanied by a certified guide dog (导盲犬)?

1. Refuse carriage on the grounds that animals are strictly barred from public motor vehicles
2. Demand that the guide dog be placed inside a locked cage in the trunk
3. Allow the certified guide dog into the passenger cabin free of charge and assist the passenger with embarkation
4. Charge double fare because a dog occupies seat space