What is a potential problem with using GETVPN for this design solution?

Your organization is working on a design solution for a new Internet-based remote access virtual private network that has 1000 remote sites A network administrator recommends GETVPN as the model because the network of today uses DMVPN, which results in a lot of background NHRP control traffic

What is a potential problem with using GETVPN for this design solution?
A . GETVPN would require a high level of background traffic to maintain its IPsec SAs
B . GETVPN requires an overlay routing control plane
C . GETVPN key servers would be on public, hacker-reachable space and need higher security
D . GETVPN is not scalable to a large number of remote sites

Answer: C

Explanation:

https://www.cisco.com/c/dam/en/us/products/collateral/security/group-encrypted-transport-vpn/GETVPN_DIG_version_2_0_External.pdf