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？（）
- APublicly Secure Packet forwarding is enabled.
- BThe minimum data rate is not set to 11 Mbps.
- CAn address resolution protocol is enabled.
- DThe access point is set to the least congested channel.