What frequency does 802.11n use?

You’re planning a wireless installation in a very populated area, and you’d like to perform an audit of existing wireless spectrum usage to avoid any conflicts. What frequency is used by 802.11n wireless networks?

A) 2.4 GHz

B) 5 GHz

C) 2.4 GHz or 5 GHz

D) 2.4 GHz and/or 5 GHz

E) Ask Kenneth