The most likely frequency range that the network consultant will have to support is 2.4GHz. This is because the most common legacy wireless standards, 802.11b and 802.11g, use the 2.4GHz range1. IEEE 802.11a uses 5GHz exclusively, and 5.9GHz and 6GHz are not widely used by legacy equipment. Therefore, A) 2.4GHz is the correct answer. https://www.networkcomputing.com/networking/wireless-beginners-part-1-rf-and-waves