Final answer:
Regression testing involves using performance and record/playback tools to ensure the existing functionality of a software system has not been affected by changes.
Step-by-step explanation:
Regression testing is the process of testing changes made to a software system to ensure that the existing functionality has not been affected. To perform regression testing, various tools can be used, including:
- Performance tools: These tools assess the performance of the system after changes have been made, ensuring that it meets the required performance criteria.
- Record/Playback tools: These tools capture and record user interactions with the system and allow them to be replayed during regression testing. This ensures that the system behaves as expected.
So, the correct answer is C. A. & B., as both performance tools and record/playback tools can be used for regression testing.