What is a transport unit in the context of CNG?

In the context of CNG, a transport unit refers specifically to a vehicle that is utilized for the transportation of compressed natural gas. This includes vehicles that are often subject to regulatory oversight and must meet certain safety standards, hence the requirement for registration with the appropriate authority, such as AFS (Aviation and Fire Safety). Understanding that transport units in this scenario are primarily designed for the delivery of natural gas underscores the importance of adherence to safety protocols and regulatory compliance in the handling of potentially hazardous materials like CNG.

The other options do not accurately represent the concept of a transport unit for CNG. Vehicles transporting solid waste or hazardous chemicals, while they operate under specific regulations, do not fall under the category defined for CNG transport. Similarly, the classification of vehicles not involved in accidents does not relate to the functionality or regulatory requirements necessary for CNG transportation. Therefore, the option indicating that vehicles must be registered with AFS aptly captures the essential criteria for classifying a vehicle as a transport unit in the CNG context.