You are troubleshooting a problem with a Cisco 7920 wireless IP phone on a standalone WLAN.The phone rings but， when you answer， the call is dropped. What may have caused this problem？（）

• A、Publicly Secure Packet forwarding is enabled.
• B、The minimum data rate is not set to 11 Mbps.
• C、An address resolution protocol is enabled.
• D、The access point is set to the least congested channel.