Why is a separate voice VLAN recommended when you use the Cisco Unified Wireless IP Phone 7920?

A.
The voice VLAN can provide Layer 3 fast secure roaming.

B.
The Cisco Unified Wireless IP Phone 7920 uses IEEE 802.11b.

C.
Appropriate ACLs can be applied to the voice VLAN.

D.
Quality of service can be applied to the voice VLAN.