Which type of bulk package may or may not be permanently attached to a motor vehicle and can be loaded or unloaded without removing the package from the vehicle?

The correct response pertains to the characteristics of a cargo tank. Cargo tanks are specialized bulk packaging designed for the transportation of hazardous materials and are constructed as part of the vehicle itself or can be mounted on the vehicle. This type of package is engineered to be filled and emptied without the necessity of detaching it from the transport vehicle, allowing for efficiency and safety during the loading and unloading processes.

Moreover, cargo tanks come equipped with safety features and controls to manage the contents effectively while on the road. This design allows them to maintain the integrity and containment of hazardous materials, making them suitable for the transportation of liquids, gases, and other materials that need secure handling.

In contrast, other types of packages, such as intermediate bulk containers, are typically removable from vehicles, while tank cars serve a different purpose in rail transport, and portable tanks often need to be taken off the vehicle to be filled or emptied. Thus, the unique capability of cargo tanks to function effectively while remaining on the vehicle is what makes this answer correct.