Which of the following is NOT a category of salvage vehicles?

The correct choice is indeed the option referring to vehicles in mint condition. In the context of salvage vehicles, categories typically include those that have been damaged but can still hold some value.

Vehicles that can be rebuilt are those that may have sustained significant damage yet have the potential to be repaired and returned to the road. Vehicles that can be used for parts are often referred to as "donor vehicles" and are dismantled to provide components for other vehicles. Lastly, vehicles that can be used for scrap are those that have little to no value left in terms of usability or parts; they are intended to be processed for the base materials.

In contrast, vehicles in mint condition would not fall under any salvage category as they retain their full market value and are not considered salvage at all. This distinguishes them clearly from the other options, which all represent vehicles that are no longer suitable for standard use on the road and thus fall into salvage classifications.