Wi-Fi commonly uses the 2.4GHz and __________________ GHz bands.

(A) 5
(B) 3
(C) 1
(D) 4

5 is the correct answer.

IEEE Standard	2.4 GHz	5 GHz	Max Data Rate
802.11	Yes	No	2 Mbps
802.11b	Yes	No	11 Mbps
802.11g	Yes	No	54 Mbps
802.11a	No	Yes	54 Mbps
802.11n	Yes	Yes	600 Mbps
802.11ac	No	Yes	6.93 Gbps
802.11ax	Yes	Yes	4x higher than 802.11ac

The 2.4 GHz band is a pretty crowded place because it’s used by more than just Wi-Fi. Old cordless phones, garage door openers, baby monitors, and other devices tend to use the 2.4 GHz band, and this can cause dropped connections and slower-than-expected speeds. The 5 GHz band is much less congested, which means you will likely get more stable connections. You’ll also see higher speeds. On the other hand, the shorter waves used by the 5 GHz band makes it less able to penetrate walls and solid objects.