单项选择题

A.network 192.168.12.0 mask 255.255.252.0
B.network 192.168.12.0 mask 0.0.3.255
C.network 192.168.12.0
D.aggregate-address 192.168.12.0 255.255.252.0
E.aggregate-address 192.168.12.0 255.255.252.0 summary-only
F.aggregate-address 192.168.12.0 255.255.252.0 as-set