What is the primary output of the odometer?

The primary function of an odometer is to measure the total distance that a vehicle has traveled over its lifetime. This measurement is typically displayed in kilometers or miles, depending on the region where the vehicle is used. As such, the correct answer pertains to the distance traveled, highlighting the odometer's role in providing essential information for vehicle maintenance, fuel efficiency calculations, and resale value assessments.

The other choices refer to different metrics that are not associated with an odometer’s function. For instance, speed is typically measured by a speedometer, and traffic weight or asphalt application involves different tools and measurements entirely. Understanding the distinction between these instruments and their specific outputs is crucial for anyone involved in fieldwork related to transportation and infrastructure.