Explanation
Decreasing the lease duration on the DHCP server will cause clients to renew their IP address leases more frequently, freeing up IP addresses for other clients to use. References: CompTIA Network+ Certification Study Guide, Chapter 3: IP Addressing.

A MAC address is a unique identifier assigned to a network interface card (NIC) that allows it to communicate on a physical network layer, such as Ethernet1. An IP address is a logical identifier assigned to a device that allows it to communicate on a network layer, such as IP2.
A technician can use different methods to find the IP address of a device if they know its MAC address. Two of the most common methods are looking at the ARP table and the DHCP leases.
The ARP table is a data structure that stores the mappings between IP addresses and MAC addresses on a device. ARP stands for Address Resolution Protocol, which is a network protocol that enables devices to discover the MAC address of another device based on its IP address3. The ARP table is populated by sending ARP requests and receiving ARP replies, or by using static ARP entries that are manually configured4.
A technician can look at the ARP table of their own device or a nearby device, such as a router or a switch, to find the IP address of a device with a known MAC address. For example, on a Windows device, the technician can use the command arp -a to display the ARP table, and look for the entry that matches the MAC address. On a Cisco device, the technician can use the command show ip arp to display the ARP table, and look for the entry that matches the MAC address.
The DHCP leases are the records of the IP addresses that are assigned by a DHCP server to DHCP clients. DHCP stands for Dynamic Host Configuration Protocol, which is a network protocol that enables devices to obtain IP addresses and other network configuration parameters automatically from a DHCP server. The DHCP leases contain information such as the IP address, the MAC address, the lease duration, and the expiration time of each DHCP client.
A technician can look at the DHCP leases of the DHCP server that serves the network segment where the device with the known MAC address is connected. For example, on a Windows DHCP server, the technician can use the DHCP console to view the DHCP leases, and look for the entry that matches the MAC address. On a Cisco DHCP server, the technician can use the command show ip dhcp binding to view the DHCP leases, and look for the entry that matches the MAC address.
The other options are incorrect for the following reasons:
C . IP route table is a data structure that stores the routes to different network destinations on a device. It does not store the MAC addresses of the devices on the network.
D . DNS cache is a data structure that stores the mappings between domain names and IP addresses on a device. DNS stands for Domain Name System, which is a network service that translates human-readable domain names into IP addresses. It does not store the MAC addresses of the devices on the network.
E . MAC address table is a data structure that stores the mappings between MAC addresses and switch ports on a switch. It does not store the IP addresses of the devices on the network.
F . STP topology is a network design that uses the Spanning Tree Protocol (STP) to prevent loops and create a loop-free logical topology on a switched network. It does not store the IP addresses or the MAC addresses of the devices on the network. Reference:
1: MAC address - Wikipedia
2: IP address - Wikipedia
3: Address Resolution Protocol - Wikipedia
4: How ARP Works
5: How to Use the Arp Command in Windows
6: show ip arp
7: Dynamic Host Configuration Protocol - Wikipedia
8: DHCP Lease
9: View DHCP Leases
10: show ip dhcp binding
11: Routing table - Wikipedia
12: Domain Name System - Wikipedia
13: DNS cache - Wikipedia
14: MAC address table - Wikipedia
15: Spanning Tree Protocol - Wikipedia

See explanation below.
Explanation
On the first exhibit, the layout should be as follows

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Exhibit 2 as follows
Access Point Name AP2
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Exhibit 3 as follows
Access Point Name AP3
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LACP (Link Aggregation Control Protocol) can be used to increase bandwidth to a server without replacing hardware. LACP allows multiple network connections to be bundled together to increase throughput and provide redundancy. This is also known as link aggregation or NIC teaming. By using LACP, the IT technician can combine multiple gigabit ports on the server to create a single high-bandwidth connection without replacing any hardware. STP (Spanning Tree Protocol), 802.1Q (VLAN tagging), and duplex settings do not increase bandwidth but rather control network topology, network segmentation, and communication speed, respectively.

A network access control (NAC) appliance is a device that checks the enrollment and compliance state of devices that try to access the network resources. It can deny, quarantine, or restrict the access of non-compliant devices based on predefined policies1. A device can be considered non-compliant if it does not meet the security requirements, such as having the latest patches, antivirus signatures, firewall settings, or encryption standards. In this scenario, the user's laptop may have been labeled as non-compliant by the NAC appliance because it was out of sync with the network policies after working remotely for a long time. The user connected to the guest network, which is usually less secure and isolated from the corporate network, and updated the patches and software, but that may not be enough to satisfy the NAC appliance. The user may need to enroll the device again, or contact the IT support to resolve the issue.
References1 - Network access control integration with Microsoft Intune | Microsoft Learn