What is the main difference between the Cisco Unified Wireless IP Phones 7921G and 7925G?

A.
The 7925G supports 802.11a/b/g, whereas the 7921G supports only 802.11b/g.

B.
The 7925G is suited for a more rugged environment.

C.
The 7925G has support for 802.11n, whereas the 7921G does not.

D.
7925G supports WPA2, whereas the 7921G supports only WPA1.