The correct answer highlights that the server handles user authentication by using username and password combinations, which is one of the most common methods for securing access to systems. This approach involves users providing their unique identifiers (usernames) and corresponding secrets (passwords) that are matched against stored credentials in a secure way.
Using username and password combinations works effectively as a basic authentication mechanism because it is straightforward for both users and systems to implement. When credentials are submitted, the server typically hashes the password and then compares it to the stored hash to verify identity. It is crucial for the storage of passwords to be secure to prevent unauthorized access, but the concept of using a simple combination of username and password remains foundational in user authentication procedures.
In contrast, other methods mentioned either add complexity or are not typically recognized as primary methods for handling authentication. For example, biometric identification relies on unique physical traits, which require specialized hardware and may pose privacy concerns. Single-sign-on methods allow users to access multiple applications with one set of credentials, but they also rely on an underlying authentication mechanism like usernames and passwords. Storing credentials in plain text is a poor security practice that compromises user safety and is never recommended as a valid method for handling authentication.