Which WLAN security feature enables clients to securely roam from one access point to another without the need to reauthenticate to the RADIUS server?

Which WLAN security feature enables clients to securely roam from one access point to another without the need to reauthenticate to the RADIUS server?

A.
CKIP

B.
TKIP

C.
CCKM

D.
802.1x

E.
WPA2