Which pattern helps in handling variable authentication methods in an application?

The Strategy pattern is ideal for handling variable authentication methods in an application because it allows developers to define a family of algorithms or strategies, encapsulate each one, and make them interchangeable. This flexibility is particularly useful in authentication scenarios where different users or situations might require different methods of authentication, such as password-based login, biometric verification, or third-party OAuth services.

By using the Strategy pattern, the application can decide at runtime which authentication method to employ, thus promoting code reuse and separation of concerns. Each authentication method can be implemented as a separate strategy, allowing for easy modifications or extensions without affecting other components of the system. This means that if a new authentication method needs to be added later, it can be done with minimal disruption to the existing codebase, adhering to open/closed principles.

In this case, while there are other patterns that serve different purposes, the Strategy pattern specifically addresses the requirement for interchangeable authentication methods, making it the most suitable choice for this scenario.