What is the fine for not wearing a seatbelt in Missouri?

In Missouri, the law states that not wearing a seatbelt results in a $10 fine for adult passengers, and wearing a seatbelt is considered a secondary offense for drivers. This means that drivers cannot be pulled over solely for not wearing a seatbelt, but if they are stopped for another violation, they can receive a fine for not wearing their seatbelt. The law emphasizes the importance of seatbelt use for safety while allowing for certain enforcement nuances concerning drivers and adult passengers. Thus, the correct answer reflects both the fine amount and the classification of the offense related to seatbelt usage.