What activity focuses on finding and removing the causes of a failure in software?

The activity that focuses on finding and removing the causes of a failure in software is debugging. Debugging involves identifying the exact location and nature of a defect in the code and systematically fixing it to ensure that the software functions as intended. This process often requires a deep understanding of the software's logic and flow, and it typically involves running the code in a controlled environment to observe its behavior, examine state variables, and use debugging tools to locate the erroneous conditions.

Testing, while essential in the software development lifecycle, primarily aims to evaluate the software for defects and verify that it meets its requirements. Testing may uncover failures but does not address the causes of those failures directly. Dynamic testing refers to executing the software to verify its behavior during runtime but does not inherently focus on fixing the issues found. Reverse engineering may be used to analyze software for various reasons, such as understanding legacy code or enhancing security, but it does not specifically aim at correcting failures in functionality.

Thus, debugging is the appropriate activity when the focus is on understanding and resolving the underlying issues that lead to software failures.