Active Gateway is the first-hop protocol feature that is used for VSX L3 gateway as per Aruba recommendation. Active Gateway is a feature that allows both VSX peers to act as active gateways for different subnets, eliminating the need for VRRP or other first-hop redundancy protocols. Active Gateway also provides fast failover and load balancing for L3 traffic across the VSX peers. The other options are incorrect because they are either not recommended or not supported by Aruba CX VSX. Reference: https://www.arubanetworks.com/techdocs/AOS-CX/10.04/HTML/5200-6728/bk01-ch07.html https://www.arubanetworks.com/resource/aruba-virtual-switching-extension-vsx/

This is the correct solution to the problem of devices behind unmanaged switches causing network outages due to loops. Loop protection is a feature that allows an Aruba CX switch to detect and prevent loops by sending loop protection packets on each port, LAG, or VLAN on which loop protection is enabled. If a loop protection packet is received by the same switch that sent it, it indicates a loop exists and an action is taken based on the configuration. Loopprotection should be configured on all edge ports of the Aruba CX 6200 and CX 6300 switches, which are the ports that connect to end devices or unmanaged switches. The trap-option should be set up to send a warning to the helpdesk when a loop is detected. The other options are incorrect because they either do not configure loop protection or do not set up the trap-option. References:
https://www.arubanetworks.com/techdocs/AOS-CX/10.05/HTML/5200-7540/GUID-99A8B276-0DA3-4458-AF
https://www.arubanetworks.com/techdocs/AOS-CX/10.05/HTML/5200-7540/GUID-D8613BDE-CD21-4B83-85

Explanation
The correct answers are C and D.
MPSK (Multi Pre-Shared Key) is a feature that allows multiple PSKs to be used on a single SSID, providing device-specific or group-specific passphrases for enhanced security and deployment flexibility for headless IoT devices1. MPSK requires MAC authentication against a ClearPass Policy Manager server, which returns the encrypted passphrase for the device in a RADIUS VSA2. ClearPass Policy Manager is a platform that provides role- and device-based network access control for any user across any wired, wireless and VPN infrastructure3. ClearPass Policy Manager can also use device profiling and posture assessment to assign roles based on device fingerprint information4.
MPSK Local is a variant of MPSK that allows the user to configure up to 24 PSKs per SSID locally on the device, without requiring ClearPass Policy Manager5. MPSK Local can be combined with EAP-TLS (Extensible Authentication Protocol-Transport Layer Security), which is a secure authentication method that uses certificates to encrypt the wireless traffic between the IoT devices and the access points6. EAP-TLS can also use device certificates to perform role-based access control6.
Therefore, both ClearPass Policy Manager and MPSK Local with EAP-TLS can meet the customer's requirements for wireless authentication, encryption, unique passphrase, and role-based access for their IoT devices.
MPSK and an internal RADIUS server is not a valid solution, because MPSK does not support internal RADIUS servers and requires ClearPass Policy Manager789. MPSK Local with MAC Authentication is not a valid solution, because MAC Authentication does not encrypt the wireless traffic or use fingerprint information for role-based access2. Local User Derivation Rules are not a valid solution, because they do not provide unique passphrase per device or use fingerprint information for role-based access101112.

According to the Aruba Documentation Portal1, 802.1X is a standard for port-based network access control that uses a RADIUS server to authenticate and authorize wireless clients. 802.1X can be configured in different modes, such as bridge mode, tunnel mode, or split tunnel mode.
Option C: GRE tunnel
This is because option C shows how to configure an SSID in tunnel mode with the default AP-group settings on an Aruba switch. In tunnel mode, all client traffic from the access points is tunneled back to the controller and the controller would in turn put the client traffic onto the network2. The GRE protocol is used to encapsulate and decapsulate the traffic between the access points and the controller3.
Therefore, option C is correct.
1:
https://www.arubanetworks.com/techdocs/AOS-CX/10.06/HTML/5200-7696/GUID-581D2976-694B-46C7-849
https://community.arubanetworks.com/discussion/bridge-and-tunnel-mode 3:
https://www.twingate.com/blog/ipsec-tunnel-mode

The auditors role is the default AOS-CX user role that meets the requirements of having Web UI access to the System > Log page and having access to the GET method for REST API for the
/logs/event resource. The auditors role has a level of 1 and allows read-only access to most commands except those related to security or passwords. It also allows access to the Web UI and REST API with limited permissions. The other options are incorrect because they either have higher levels of access or do not allow access to the Web UI or REST API.