(a) A person who is 18 years of age or older and who is licensed by the department to operate a motor vehicle as a school bus may operate the motor vehicle for the transportation of junior college students and employees to and from school or official school activities.
(b) A school bus operated by a junior college may also be used to transport public school students if it is convenient. If students of a local public school district are transported to and from school on a bus operated by a junior college and the operator is under 21 years of age, the selection of the operator must be approved by the principal of the public school whose students are transported on that bus.
(c) This section does not apply to the operator of a vehicle operated under a registration certificate issued under Chapter 643.