Which of the following is considered a used vehicle?

The correct answer encompasses both the definition provided in option A and the details in option B. A used vehicle is generally any vehicle that has been previously owned and sold, which includes vehicles that may have been purchased by a dealership and later resold. This means that a demo vehicle with 1500 miles, as noted in option B, would also be categorized as a used vehicle because it has been driven and is no longer in its original condition as a new vehicle.

Further context shows that while option D states that any vehicle older than one year is considered used, this definition can be somewhat misleading. A vehicle that is one year old might still be in the category of a "new" vehicle if it was purchased and registered within that year. Therefore, the most accurate definition includes both previously owned vehicles and demo models, which makes option C the comprehensive choice in identifying what constitutes a used vehicle.