You have created a baseline metric， DISK_IO_BL， for the disk I/O metrics in your PROD database and you have been getting notifications whenever the database performance degrades. You optimize the database I/O to gain the performance and you decide to remove the baseline metrics. Which method would you use to remove the DISK_IO_BL baseline metrics？（）

• A、The baseline， once created， cannot be removed.
• B、Disable the baseline metrics in the Database Control Manage Metrics page.
• C、The baseline will be automatically removed once the database performance has been optimized.
• D、Drop the baseline metrics by usingDBMS_WORKLOAD_REPOSITORY.DROP_BASELINE procedure.