Pre-K Bus Passengers

If my child rides a bus, I agree to make sure an adult is present at the bus stop to put the child on the bus each morning.  I also agree to make sure that an  adult is present in the afternoon to take the child off the bus.  I  unstand that if an adult is not present, the student will not be allowed to get off the bus and will be returned to the bus shop or the school and parents will be called to come for child.  Pre-K students are not allowed to get off  the bus with another student under 18 years of age.