Which of the following is true about Corrective Maintenance?

• A. It includes modifications and updations done in order to correct or fix problems, which are either discovered by user or concluded by user error reports.
• B. It includes modifications and updations applied to keep the software product up-to date and tuned to the ever changing world of technology and business environment.
• C. It includes modifications and updates done in order to keep the software usable over long period of time.
• D. It includes modifications and updations to prevent future problems of the software.