Step-by-step explanation:
The replacement device should support 802.11ac to BEST fulfill the customer's needs.
802.11ac is the latest and fastest Wi-Fi standard that operates in the 5 GHz frequency band and supports multi-user MIMO technology, which allows for simultaneous data transmissions to multiple devices. It is capable of providing faster wireless speeds and improved performance, which is important to the customer's request to increase wireless speed.
802.11b, 802.11a, and 802.11g are older Wi-Fi standards that operate in the 2.4 GHz frequency band and have slower maximum speeds and less reliable performance.