How can you achieve optimum failover without affecting any other router in the DMVPN cloud?

A spoke has two Internet connections for failover. How can you achieve optimum failover
without affecting any other router in the DMVPN cloud?

A.
Create another DMVPN cloud by configuring another tunnel interface that is sourced from
the second ISP link.

B.
Use another router at the spoke site, because two ISP connections on the same router for
the same hub is not allowed.

C.
Configure SLA tracking, and when the primary interface goes down, manually change the
tunnel source of the tunnel interface.

D.
Create another tunnel interface with same configuration except the tunnel source, and
configure the if-state nhrp and backup interface commands on the primary tunnel interface.