Which of the following options is a method Google Analytics employs to track user demographics?

Google Analytics utilizes cookies and device identifiers as a fundamental method to track user demographics. Cookies are small pieces of data stored on the user's browser that allow Google Analytics to collect information about user interactions on a website. This includes details such as the user's location, device type, and browsing behavior. Device identifiers further enhance tracking by uniquely identifying devices, which helps in understanding demographic trends among users.

This method provides a broad overview of user demographics without requiring individuals to directly reveal personal information. In contrast, the other methods mentioned would involve more direct user input or interaction which Google Analytics typically does not rely on for demographic data gathering. Collecting this kind of information would raise privacy concerns and require explicit user consent, which is not the standard practice in Google Analytics tracking. Thus, cookies and device identifiers effectively balance data collection and user privacy, making them the most appropriate choice for tracking demographic information.