The selection of test cases for regression testing requires a comprehensive approach. It involves understanding the bug fixes and their impact on the system to ensure that the fixes work as intended and do not introduce new issues. It also includes focusing on areas with frequent defects, as these are more prone to issues and need thorough testing. Additionally, areas that have undergone many or recent code changes are critical to test because changes in the code can have unforeseen impacts. Therefore, the correct answer includes knowledge on bug fixes, frequent defects, and recent code changes, making 'All of the above' the most appropriate choice.