Which option is an invalid configuration file name format for Cisco WLC auto-provisioning? Select the best response

Which option is an invalid configuration file name format for Cisco WLC auto-provisioning? Select the best response.

A.
<hostname>.cfg

B.
<hostname>-confg

C.
ciscowlc-confg

D.
ciscowlc.cfg

E.
<ip-address>.cfg

F.
<serial number>-confg