When changing legacy code, the recommended approach in Disciplined Agile is to "Add a test first, then change it." This practice is aligned with Test-Driven Development (TDD) and ensures that any modifications made to the legacy code do not introduce new defects. By writing tests before making changes, you establish a safety net that confirms the existing functionality remains intact, and the new changes work as expected.
Rewriting the code (B), delegating the task (C), or changing the code before adding tests (D) can increase risk and are not recommended practices.