The likely cause of the issue of weak Wi-Fi coverage in the office is that the AP is using a directional antenna.
A directional antenna is an antenna that radiates or receives radio waves more strongly in one or more directions, creating a focused beam of signal. A directional antenna can provide better coverage and performance for a specific area, but it can also create dead zones or weak spots for other areas. The other options are incorrect because they eitherdo not affect the Wi-Fi coverage or do not match the scenario.
References:
https://www.arubanetworks.com/techdocs/ArubaOS_86_Web_Help/Content/arubaos-solutions/wlan-rf/rf-fundam

The capability that enables plug-and-play provisioning of access points in an HPE Aruba network is the UCC Service. The UCC Service is a cloud-based service that allows the access points to automatically discover and connect to the Aruba Central management platform without any manual intervention. The UCC Service also provides zero-touch configuration, firmware updates, and monitoring for the access points.

The Aruba CX 6400 switch is a modular switch that supports high-performance and high-density Ethernet switching for campus and data center networks. One of the features that distinguishes the Aruba CX 6400 switch from most typical campus switches is virtual output queueing (VOQ). VOQ is a technique that implements large ingress packet buffers on each port to prevent head-of-line blocking and packet loss due to congestion2. VOQ allows each port to have multiple queues for different output ports and prioritize packets based on their destination and QoS class2. VOQ enables the Aruba CX 6400 switch to achieve high throughput and low latency for various traffic types and scenarios. References: 2 https://www.arubanetworks.
com/assets/ds/DS_CX6400Series.pdf

The system-mac command is used to configure a fixed MAC address for the VSX system. This MAC address is used as the source MAC address for all routed traffic from the VSX node. The system-mac command is highly recommended for preventing traffic disruptions when the primary VSX switch restores after the secondary VSX switch, such as during a primary switch hardware replacement or a power outage2. During the initial VSX configuration, the system-mac is assigned with a fixed MAC based on VSX ID. The system- mac command can be used to change this default MAC address if needed2. Therefore, answer D is correct.
References: 1: Aruba Campus Access documents and learning resources 2: system-mac - Aruba

AOS 10 Gateways can have the following personas: Mobility, Branch, and VPN Concentrator1 However, the Mobility persona is only available when configuring a Gateway-onlygroup, which is a group that contains only one gateway device2 The Mobility persona provides Overlay WLAN and (or) wired LAN functionalities for campus networks1 The Branch persona provides the Aruba Instant OS and SD-Branch (LAN + WAN) functionality for branch and microbranch networks1 The VPN Concentrator persona provides VPN termination and routing functionality for remote access networks3 The Edge persona is not a valid option, as it is not a supported device persona for AOS 10 Gateways.