Answer:
802.11n uses this frequency
It is mostly interference-free
Explanation:
Among the listed Wi-Fi standards, 802.11n uses the 5 GHz frequency, not 802.11n. And it is true that it is mostly interference free, as interference mostly happens when 2.4 GHz frequency comes across devices that may interfere with the signal, such as microwaves, TVs, etc... The 5 GHz frequency has bigger bandwidth than 2.4 GHz, but the latter has higher coverage.
