Final answer:
It is true that a holder of a valid G2 certificate is authorized to work on the carburetion system of a propane powered highway vehicle, as this certification indicates specialized training and competence in handling such systems.
Step-by-step explanation:
The holder of a valid G2 certificate is authorized to work on the carburetion system of a propane powered highway vehicle. This statement is true. A G2 certificate typically indicates that an individual has received specialized training and has been tested on their competence to service and repair propane fuel systems. This certificate is usually required by law for anyone working on such systems to ensure safety standards are met, as working with propane can be hazardous if not done correctly. Therefore, a person with a G2 certification is considered qualified to work on the carburetion systems of propane-powered vehicles.