Which of the following can be adjusted to improve wireless network performance when multiple networks...

Channel width can be adjusted to improve wireless performance when multiple nearby networks are competing for radio spectrum. Wider channels can provide greater theoretical throughput, but they consume more spectrum and are more likely to overlap with neighbouring networks. In a congested environment, reducing the channel width—for example, from 40MHz to 20MHz on the 2.4GHz band—can reduce interference, retransmissions, and channel contention. The correct configuration therefore depends on the surrounding wireless environment, but channel width is the only listed setting that directly affects spectrum usage and performance. Hiding the SSID merely prevents the network name from appearing in ordinary discovery lists and does not reduce interference. MAC filtering is an access-control mechanism and provides no meaningful performance improvement. AES is an encryption algorithm used with wireless security protocols; it protects traffic confidentiality but does not resolve overlapping-channel or congestion problems.