How wide is each of the three WLAN U-NII bands?

• A. 50 MHz
• B. 100 MHz
• C. 200 MHz
• D. 400 MHz

Answer: (B)

The main idea is that the 5 GHz WLAN spectrum used for U-NII bands is divided into fixed 100‑MHz blocks. Each of the three U‑NII bands is a single contiguous 100‑MHz range, which is why you’ll see 100 MHz cited as their width. This block structure makes it easy to plan channel options: standard 20 MHz channels fit within a 100‑MHz block, and you can bond multiple blocks to create wider channels (40, 80, or 160 MHz) as allowed by regulations and the device. So the best answer is 100 MHz because that is the actual block width of each U‑NII band.