按照美国制定的光纤通信标准SONET，OC-48的线路速率是______Mb/s。

A．138.138.203.0
B．138.138.205.0
C．138.138.207.0
D．138.138.213.0

A．network 192.100.10.5 0.0.0.3 area 0
network 192.1.0.129 0.0.0.63 area 1
B．network 192.100.10.4 0.0.0.3 area 0
network 192.1.0.128 0.0.0.63 area 1
C．network 192.100.10.5 255.255.255.252 area 0
network 192.1.0.129 255.255.255.192 area 1
D．network 192.100.10.4 255.255.255.252 area 0
network 192.1.0.128 255.255.255.192 area 1