What is a common reason for performing regression testing?

Regression testing is primarily performed to ensure that any changes made to the software, such as bug fixes or new features, have not adversely affected existing functionalities. When new code is integrated or existing code is modified, there is a risk that these changes might unintentionally disrupt or degrade the performance of features that have previously been working correctly.

By conducting regression testing, testers can identify and resolve any issues that arise from these changes, ensuring that the software maintains its expected behavior and performance after updates. This form of testing is crucial in maintaining the integrity of the software application throughout its lifecycle, particularly in agile development environments where changes may be frequent and rapid.

In contrast, the other options focus on different aspects of testing: validating new features aligns more with functional testing; assessing performance involves performance testing; and confirming accessibility relates to usability and compliance testing. Each of these serves different purposes within the testing processes, but regression testing specifically addresses the concern of maintaining quality in already functioning components after updates.