What is the primary purpose of Regression Testing? 

Regression Testing is performed after changes are made to a software system to ensure that previously developed and tested functionalities still work as expected. This is especially important when new features are added, bugs are fixed, or changes are made to the codebase. By re-running previous test cases, regression testing helps catch unintentional errors introduced by recent code changes. Why other options are wrong: a) Unit Testing : Tests individual components or functions, not regression. b) Integration Testing : Ensures that different modules work together, but does not focus on detecting new errors in existing functionality. d) User Acceptance Testing (UAT) : Verifies if the software meets business needs from the user’s perspective. e) Performance Testing : Focuses on measuring system performance metrics, not regression errors.