An Administrator Is Concerned About the Security of the Control

An administrator is concerned about the security of the control plane connection between an AOS-CX switch and an Aruba Mobility Controller (MC) when implementing user-based tunneling. How should the administrator protect this traffic?

A) IPSec with a digital certificate
B) GRE with a pre-shared key
C) PAPI with an MD5 pre-shared key
D) IPSec with a pre-shared key