下面哪个是正确的默认路由(default route)

下面哪个是正确的默认路由(default route)

A.route ip 172.0.0.0 255.0.0.0 s0

B.ip route 0.0.0.0 0.0.0.0 172.16.20.1

C.ip route 0.0.0.0 255.255.255.255 172.16.20.1

D.route ip 0.0.0.0 255.255.255.0 172.16.10.11 50

正确答案是B