The statistics for a poorly performing， dual-processor x365 system are as follows：     （1）Processor： 80% for 5-second increments   （2）Memory page faults： 360/second average over 15 minutes       （3）Disk % disk time： 100%   Which of the following will provide the greatest performance improvement？（）

• A、Add memory
• B、Add a processor
• C、Exchange the existing processor for a faster processor
• D、Add a faster disk subsystem