What configuration issue is most likely contributing to the problem?

After a wireless deployment, users report that wireless voice clients are experiencing an unacceptable amount of delay while roaming during a call on the Cisco Unified 7925 Series phones. The customer environment consists of multiple controllers, all running 7.4.121.0 code, operating in a centralized deployment.
What configuration issue is most likely contributing to the problem?
A. The authentication should be set to WPA2-PSK to allow for 802.11n speeds for the Cisco Unified 7925 phones.
B. The access points on that floor are all on one controller and should be load balanced evenly across multiple controllers.
C. The access points for that floor are salt and peppered across multiple controllers and should be moved to the primary controller.
D. The wireless phones are operating in the 2 4 GHz band and should be configured for the 5 GHz band.