A user named Tom reports that an application on his Windows 2000 Professional computer is running slowly. You notice Tom’s computer has 64 MB of RAM and 100 MB of free disk space. What should you do to improve the performance of his system？ （）

• A、Add Tom to the Power user group.
• B、Set the total paging file to 75 % of physical memory.
• C、Perform a disk analysis and use the disk defragmenter if recommended.
• D、Use Disk cleanup to delete temporary files and unnecessary program files.
• E、Ensure that the Performance Options windows is optimized for background services.