The best option to install security updates on multiple switches is to use a TFTP (Trivial File Transfer Protocol) server and SSH (Secure Shell) connections. A TFTP server is a simple and lightweight file server that can host the update files and transfer them to the switches over the network. SSH is a secure and encrypted protocol that can be used to remotely access and configure the switches. The technician can use SSH to log into each switch, download the update file from the TFTP server, and apply the update. This method is faster and more efficient than using a terminal emulator and a console cable, which would require physical access to each switch and a serial connection. It is also more cost-effective and less disruptive than replacing the switches with new ones. Using a USB memory stick is also possible, but it would still require physical access to each switch and a USB port, which may not be available on all models.
Reference:
[CompTIA Network+ N10-008 Certification Study Guide], Chapter 5: Network Operations, Section 5.4: Firmware Updates, pp. 283-284
[Professor Messer's CompTIA N10-008 Network+ Course Notes], Section 5.4: Firmware Updates, p. 71
[Professor Messer's CompTIA N10-008 Network+ Training Course], Video 5.4: Firmware Updates, 9:07 minutes

A change management policy is a document that outlines the procedures and guidelines for making changes to a network or system, including how changes are approved, tested, and implemented. By following a change management policy, organizations can ensure that unnecessary modifications to the network are not permitted and version control is maintained. Reference:
Network+ N10-008 Objectives: 1.6 Given a scenario, implement network configuration and change management best practices.

802.11g is an older wireless standard that operates in the 2.4 GHz frequency band and has a maximum data rate of 54 Mbps. 802.11a is a newer wireless standard that operates in the 5 GHz frequency band and has a maximum data rate of 54 Mbps. By configuring the APS to be compatible with 802.11a, the network engineer can reduce interference and congestion in the 2.4 GHz band and improve wireless performance.
References: Network+ Study Guide Objective 2.5: Implement network troubleshooting methodologies

QSFP+ is a transceiver type that can support up to 40Gbps. It stands for Quad Small Form-factor Pluggable Plus and uses four lanes of data to achieve high-speed transmission. It is commonly used for data center and high-performance computing applications. References:
https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/transceiver-modules/data_sheet_c78-6600