单项选择题

A. It indicates that the radio of the client adapter is disabled.
B. It indicates that the client adapter is not associated to an access point or another client. 
C. It indicates that the client adapter is associated to an access point or another client, but the user is not  EAP authenticated.
D. It 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.
E. It 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.
F. It 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.