Final answer:
Juvenile offenders are primarily motivated by the thrill of joy riding when committing motor vehicle theft, as opposed to more sophisticated crimes driven by financial gains.
Step-by-step explanation:
The primary motivation for motor vehicle theft committed by juvenile offenders is often joy riding. This type of theft is not typically motivated by financial gain but rather by the thrill and excitement of driving a car without permission.
While other options like profit through resale, insurance fraud, and grand theft auto may motivate some vehicle thefts, they generally require a level of sophistication and criminal intent that is less common among juveniles engaging in impulsive or opportunistic crimes.