Which statement about Cisco CleanAir technology is true?

Which statement about Cisco CleanAir technology is true?

A.
It features chip-level proactive and automatic electronic beamforming.

B.
It features automatic advanced radio frequency shaping.

C.
It features chip-level proactive and automatic interference mitigation.

D.
It is a feature of the Cisco Aironet 1600 Series AP

Explanation:
http://www.cisco.com/en/US/solutions/collateral/ns340/ns394/ns348/ns1070/aag_c22-

594304.pdf