During the inspection process, what function does a quarter serve?

Using a quarter during the inspection process serves as a practical tool for checking small parts and gaps, particularly in tires. The quarter can be inserted into the tread of a tire to quickly assess whether there is sufficient tread depth. If the quarter disappears into the tread, it indicates that the tires have adequate depth and are safe for use. This method is a simple visual and tactile inspection that helps identify tires that may be worn down and unsafe for driving, ensuring the vehicle remains compliant with safety standards.

While the other functions listed in the choices have their specific purposes, they do not involve the use of a quarter directly. Testing battery voltage typically requires a voltmeter or other testing equipment. Measuring tread depth generally relies on specialized gauges rather than loose change, and assessing hydraulic pressure requires pressure gauges suited for that purpose. Therefore, the role of the quarter is clearly tied to inspecting small gaps and parts, specifically related to tire tread.