A user named Tom reports that applications on his Windows 2000 Professional computer are running slowly. You notice that Tom’s computer has 64 MB of RAM and 100 MB free disk space. Which method can you use to improve performance？（）

• A、Add Tom to the Power Users group.
• B、Set the total paging file to 75 percent 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 setting is optimized for background services.