Refer to the exhibit. A Cisco Aironet Wireless LAN Client Adapter has been installed and configured through the ADU on the PC. The Aironet System Tray Utility （ASTU） has been enabled during the installation and the icon appears in the system tray area in the lower right of the desktop. What is thesignificance of the icon？（）
- AIt indicates that the radio of the client adapter is disabled
- BIt indicates that the client adapter is not associated to an access point or another client
- CIt indicates that the client adapter is associated to an access point or another client， but the user is not EAP authenticated
- DIt indicates that the client adapter is associated to an access point or another client， that the user is authenticated if the client adapter is configured for EAP authentication， and that the signal strength is excellent or good
- EIt indicates that the client adapter is associated to an access point or another client， that the user is authenticated if the client adapter is configured for EAP authentication， and that the signal strength is fair
- FIt indicates that the client adapter is associated to an access point or another client， that the user is authenticated if the client adapter is configured for EAP authentication， and that the signal strength is poor