Regarding DMVPN and FlexVPN, which statement is correct?

The correct statement is that FlexVPN uses IKEv2 for key management, while most traditional DMVPN deployments use IKEv1. FlexVPN was designed with IKEv2 as its foundation, offering improvements like simplified negotiation, built-in NAT traversal, and better reliability. While DMVPN can be configured with IKEv2, its initial and most common implementations relied on IKEv1. The second option is incorrect because it reverses the IKE version usage. The third option is incorrect; FlexVPN simplifies DMVPN's multi-phase model by integrating routing and NHRP into a more streamlined IKEv2 negotiation, rather than defining more phases. The fourth option is incorrect as both DMVPN and FlexVPN are primarily deployed on Cisco routers, not exclusively firewalls.