What speeds must be disabled in a mixed 802.11b/g WLAN to allow only 802.11g clients to connect?

What speeds must be disabled in a mixed 802.11b/g WLAN to allow only 802.11g clients to
connect?

A.
6, 9, 12, 18

B.
1, 2, 5.5, 6

C.
5.5, 6, 9, 11

D.
1, 2, 5.5, 11