A user explains that after the office was vacuumed the previous night their sound is not working and they cannot get onto the network. The user has verified that all of the PC’s cables are plugged into their respective ports. Which of the following is the MOST likely cause?（）

• A、Frayed or broken cables
• B、UPS is unplugged
• C、NIC and sound card are disabled in Device Manager
• D、Speakers are muted