which alternative Cisco IOS method is available if GRE-over-IPsec tunnels could not be used?

While performing point-to-point secure WAN solutions over the Internet, which alternative Cisco IOS method is available if GRE-over-IPsec tunnels could not be used?

A.
Dynamic crypto maps

B.
Virtual Tunnel Interfaces (VTIs)

C.
GET VPN

D.
MPLS VPN