Which entry in the public (external) DNS is valid to configure DNS SRV records for a Cisco Mobile and Remote Access solution?

Which entry in the public (external) DNS is valid to configure DNS SRV records for a Cisco Mobile and Remote Access solution?
A. _cisco-uds._tcp.
B. _cisco-mra._tls.
C. _collab-edge._tls.
D. _cisco-expwy._tls.