Which authentication method does PAM primarily utilize for system access management?

PAM, or Pluggable Authentication Modules, primarily utilizes username and password combinations as a fundamental method for system access management. This framework is designed to provide a flexible way of implementing authentication in Linux systems by allowing the integration of various authentication technologies.

The primary role of PAM is to handle the management of user authentication using a variety of methods, but at its core, it typically starts with the simplest and most widely used form: the combination of a username and password. When a user attempts to gain access, PAM checks the provided username against the system's user database and validates the password.

While PAM is capable of supporting multi-factor authentication, biometric verification, and token-based verification by employing additional modules, these are not its primary method. Instead, the framework is constructed around the essential practice of username and password combinations, which serves as the initial barrier to access before any additional authentication measures may be applied.