Which of the following describes a condition under which a vehicle is compliant with state law for transporting explosives?

Answer: C — Mounting a red flag of at least 12 inches square on the rear

A vehicle transporting explosives must meet specific safety requirements to comply with state law. One of these requirements is to ensure visibility and warning to other road users regarding the hazardous materials being transported. Mounting a red flag of at least 12 inches square on the rear of the vehicle serves this purpose by signaling to others that the vehicle is carrying explosives. This visible cautionary measure helps prevent accidents and enhances overall safety on the road. The other options, while possibly relevant to vehicle safety or regulatory compliance in different contexts, do not specifically address the required conditions for transporting explosives. For instance, warning lights and reflective tape may be beneficial for general visibility but are not necessities that confirm compliance with explosive transport regulations. Similarly, safety stickers provide useful information but do not serve the particular purpose of alerting others to the dangerous cargo being transported.