单项选择题

A.业务发送方向:SDH signals->LSX->M40V->OBU1->Line
B.OSC接收方向:Line->FIU->Sc2
C.业务接收方向:Line->FIU->OAU->M40V->LSX->SDH signals
D.业务发送方向:SDH signals->LSX->M40V->OBU1->FIU->Line