Your customer wants to make sure that only computers he has authorized can get on his Wi-Fi. What is the most appropriate security measure you can recommend?

A firewall filters traffic between networks based on rules but does not prevent unauthorized devices from associating with the Wi-Fi access point.

WPA encryption protects data in transit and requires a passphrase, but any device with the correct passphrase can connect; it does not restrict access to specific authorized computers.

WEP encryption is an outdated and cryptographically weak protocol that, like WPA, does not restrict access to specific authorized devices.

MAC filtering works by allowing the wireless access point to maintain a list of permitted MAC addresses; only devices with a matching hardware address are granted network access regardless of credentials. This is the most direct technical control for authorizing specific computers by their unique hardware identifiers. Other options provide encryption or traffic filtering but do not control which devices are permitted to associate.