What must be clearly marked in buses?

You answered correctly. In buses, both the location of the first-aid kits and the seats reserved for severely disabled persons must be clearly marked. This ensures that, in an emergency, passengers and staff can quickly find the first-aid kit, and that those who need priority seating can easily identify and access these designated seats. Marking the on-board tools is not required. Knowing these requirements helps ensure safe and accessible public transport for everyone.