Which item is restricted and requires documentation?

Firearms are restricted items that require specific documentation due to their regulated nature and the potential risks associated with their possession and use. In many jurisdictions, firearms are subject to strict laws governing their sale, ownership, transfer, and transportation. This documentation may include licenses, permits, or a record of sale to ensure accountability and compliance with legal standards.

These regulations are put in place to prevent unlawful use and to promote public safety. In contrast, while some of the other items like soil and dog fur might have their own regulations depending on the context (such as agricultural or import regulations), they do not typically have the same stringent requirements as firearms. Airplane parts may require documentation related to safety and maintenance in an aviation context, but they are not classified as restricted items in the same way firearms are.