Which testing methods are available for observing applications with synthetic users?

The correct answer highlights the testing methods specifically geared towards observing applications with synthetic users. API Tests and Browser Tests are both designed to simulate user interactions and monitor application performance effectively.

API Tests allow for the validation of application programming interfaces, checking the integrity and functionality of back-end services by simulating requests made by users. This helps ensure that the API responds as expected, aiding in performance monitoring and reliability.

Browser Tests simulate real user interactions with a web application. By replicating actions such as clicking buttons, filling out forms, or navigating pages, these tests help in monitoring the user experience directly from a web browser perspective. This approach provides insights into how an application performs in a real-world scenario from a user's viewpoint.

Both of these testing methods play crucial roles in synthetic monitoring, as they allow teams to proactively identify issues, optimize performance, and enhance the reliability of applications before users encounter problems.

Other options do not fully capture the essence of synthetic user observation in the context specified. For instance, while load tests are aimed at assessing system performance under heavy usage, they do not simulate individual user interactions as closely as Browser Tests. Similarly, unit tests focus on validating individual components of the codebase and are more suitable for developers rather than monitoring application performance from a user experience