While performing a preventative maintenance check on a personal computer, a technician notices thatseveralunused expansion card slots have open ports. Which of the following BEST describes why the covers for these card slots should be reinstalled?（）

• A、Help limit radio frequency interference (RFI) inside the case.
• B、Help ensure proper air flow through the case.
• C、Help prevent moisture buildup in the case.
• D、Help limit electrostatic discharge (ESD) inside the case.