The system administrator has been getting complaints about slow performance from the server. After running vmstat the administrator notices average readings that show the free list （fre） approaching zero， as well as page-in （pi） and page-out （po） values to be high. Furthermore， the applications running are essential to daily business operations. Which of the following recommendations would provide the best overall improvement？（）

• A、 Increase physical disk
• B、 Increase number of CPU’s
• C、 Increase physical memory
• D、 Increase number of servers