Given the output showing a real-time debug, the statement that describes the login failure is:
C. student is not part of the usergroup SSL_VPN_Users: The debug log contains a line that says "fnbam_cert_check_group_list-checking group with name 'SSL_VPN_Users'" followed by "peer_check_add_peer_check_student" and later "RDN_match-Checking 'CN' val 'STUDENT' -- no match." This suggests that the certificate presented has a common name (CN) of 'student', which does not match or is not authorized under the 'SSL_VPN_Users' group expected for successful authentication.