Vehicles requiring reflectors must mount them in accordance with which guideline?

Answer: C — State-mandated height requirements

Vehicles requiring reflectors must follow state-mandated height requirements for their installation because this ensures visibility and safety on the road. State regulations typically specify where reflectors should be placed to maximize their effectiveness, helping other drivers to see the vehicle clearly, especially in low-light conditions or at night. This approach is essential for road safety and compliance with traffic laws, and it standardizes reflector placement across different vehicles, reducing confusion for other road users. Following these guidelines helps to ensure that vehicles are in compliance with regulations, promoting safe driving practices and reducing the likelihood of accidents. In contrast, options like manufacturer instructions or the owner's preference may not always align with state regulations, potentially leading to ineffective reflector placement that could compromise safety.