Which statement best describes 802.11ac relative to 802.11ax?

• A. It uses wider channels but fewer spatial streams
• B. It introduces OFDMA for efficiency
• C. It supports more MU-MIMO streams than 802.11ax
• D. It operates only in 2.4 GHz

Answer: (D)

The main idea is how the two standards use the spectrum and how they handle efficiency and multiple devices. 802.11ac achieves high throughput mainly by bonding wider channels in the 5 GHz band and using MIMO, but it does not introduce OFDMA. 802.11ax builds on that by adding OFDMA to subdivide channels and schedule resources more efficiently, and it extends operation to both 2.4 GHz and 5 GHz (with 6 GHz added in Wi‑Fi 6E). So saying that 802.11ac operates only in 2.4 GHz is not correct—the standard is primarily 5 GHz. The other statements don’t accurately describe the real differences: OFDMA is a 802.11ax feature, 802.11ax generally supports at least as many MU‑MIMO streams and more efficiency in crowded environments, and 802.11ac does not shift to 2.4 GHz as its sole band.