Explanation
The RFC1918 IP space is a set of private IP addresses that are not routable on the public Internet and can be used for internal networks. The RFC1918 IP space consists of three ranges: 10.0.0.0/8, 172.16.0.0/12, and
192.168.0.0/161 Out of the four options, only A. 10.10.10.0/24 belongs to one of these ranges, specifically the
10.0.0.0/8 range. Therefore, the technician should use this subnet for the LAN.
References1: https://en.wikipedia.org/wiki/Private_network

Explanation
A wireless controller would be able to handle the requirement of implementing a large number of WAPs throughout the building and allowing users to move around without dropping their connections. A wireless controller is a device that centrally manages and configures multiple wireless access points (WAPs) on a network. It can provide features such as load balancing, roaming, security, QoS, and monitoring for the wireless network. A wireless controller can also support wireless mesh networks, where some WAPs act as relays for other WAPs to extend the wireless coverage. References:
https://www.cisco.com/c/en/us/products/wireless/wireless-lan-controller/index.html

Explanation
CRC stands for Cyclic Redundancy Check, and it is a type of error-detecting code used to detect accidental changes to raw data. If the CRC count is increasing on a particular interface, it indicates that there might be an issue with the cabling, which is causing data corruption. References:
Network+ N10-008 Objectives: 2.1 Given a scenario, troubleshoot common physical connectivity issues.