Which of the following options is NOT considered a penalty for littering in Guam?

The correct choice highlights that purchasing an eco-friendly vehicle is not a recognized penalty for littering in Guam. Penalties for littering are typically designed to deter harmful behaviors and encourage responsible environmental practices. These include monetary fines that impose a financial penalty for the infraction, community service that requires individuals to contribute positively to the community, and law enforcement warnings that serve to educate offenders about the consequences of their actions without formal punishment on the first violation.

In contrast, requiring the purchase of an eco-friendly vehicle does not directly relate to addressing or punishing the act of littering. Instead, it focuses on promoting environmentally friendly choices, which, while beneficial, does not serve as a direct consequence for littering.