A medical customer has a rack with four BladeCenter H chassis that have been operating normally for several months. After installing a new rack of servers in the data center, the system administrator notices the blowers in the BladeCenters have increased their speed. Which of the following caused this problem? （）

• A、The room temperature has reached 23C (73.4F). 
• B、A Blade within the chassis has been shut down. 
• C、The ambient temperature in the data center has increased 
• D、One of the additional System X servers in the BladeCenter rack has failed.