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 cause this problem？（）
A. The minimum data rate is not set to 11 Mbps.
B. An address resolution protocol is enabled.
C. Publicly Secure Packet forwarding is enabled.
D. The access point is set to the least congested channel.
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