What is a possible reason for the ErrorCode ‘Failed to classify request to service’ shown?

Refer to the exhibit.

An administrator configured a service and tested authentication, but was unable to complete authentication successfully. The administrator performs a Search using insight and the information displays as shown.

What is a possible reason for the ErrorCode ‘Failed to classify request to service’ shown?
A . The user failed authentication due to an incorrect password.
B . ClearPass could not match the authentication request to a service, but the user passed authentication.
C . ClearPass service authentication sources were not configured correctly.
D . The NAD did not send the authentication request.
E . ClearPass service rules were not configured correctly.

Answer: E