Which testing approach responds dynamically to the behavior of a test object?

Reactive testing is characterized by its focus on dynamically responding to the behavior of the test object during the testing process. This approach is particularly useful in agile environments where requirements and implementations may evolve rapidly. By observing the actual performance and behavior of the application as it is being tested, testers can immediately identify any issues or unexpected behaviors. This flexibility allows for adjustments in testing strategies based on real-time feedback, ensuring that the testing effort remains aligned with the current state of the software being developed.

In contrast, proactive testing involves anticipating potential issues before they arise and planning tests accordingly, while static testing centers on examining the code or documentation without executing the code. Exploratory testing, although dynamic in nature, emphasizes unscripted and session-based test execution rather than directly responding to behavior, which makes reactive testing the more appropriate choice in this context.