The correct answer is To verify that recent code changes do not introduce defects into existing features.

To verify that recent code changes do not introduce defects into existing features is the core purpose of regression testing because the team must retest previously working functionality after updates. Regression tests detect unintended side effects from code changes so that authentication workflows, input validation, access controls, and other security relevant features continue to function as expected.

To use automated scanners to detect vulnerabilities is incorrect because automated scanning is a vulnerability discovery activity and not the main focus of regression testing. Scanners may be used during a regression cycle but they do not define the primary goal.

To confirm that security patches have not reintroduced previously fixed flaws is incorrect because that statement is a narrower case that focuses on reintroduced fixes. Regression testing covers broader verification of existing features after any code change rather than only checking for reintroduced patches.

To validate cryptographic implementations and algorithm usage is incorrect because validating cryptography is a specialized task that requires design review and targeted testing. That activity is separate from regression testing which focuses on functional stability across the application.

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