A project's QA team needs to validate functionality in a timely and cost-effective way to...

Because the team needs validation every time a new change is integrated, the priority is repeatability, speed, and consistent coverage—this is where automated testing is most effective. CompTIA Project+ explicitly calls out testing approaches as Automated vs. Manual within operational change-control and release practices, reinforcing that automation is a key control to support frequent integration and deployment.

While regression testing is the type of testing that checks whether new changes broke existing functionality, doing it manually every integration is often slow and expensive. Automation enables the regression suite (and other checks) to run quickly in CI/CD pipelines, improving coverage and reducing per-run effort, which matches the question’s “timely and cost-effective” requirement. CompTIA also lists regression testing among testing cycles, but the scenario’s emphasis is on executing that validation repeatedly with efficiency—best achieved by automation.

Sanity testing is usually a quick, narrow check after a change; it does not provide the broad “good coverage” implied here. Therefore, establishing automated testing is the best answer to ensure consistent, repeatable validation whenever changes are integrated.