单项选择题
Thedispersionofanon-zerodispersionshiftedfiberis6ps/nm*kmat1550nmand10ps/nm*kmat1610nm.WhatistheminimumdispersioncompensationrequiredifanL-BandDWDMsignaltravelsthrough200kmoffiberandhasadispersiontoleranceof1800ps/nm？（）
A.none
B.-600ps/nm
C.-200ps/nm
D.+200ps/nm
E.+600ps/nm
A.WhatistheminimumdispersioncompensationrequiredifanL-BandDWDMsignaltravelsthrough200kmoffiberandhasadispersiontoleranceof1800ps/nm？（）
A.none
B.-600ps/nm
C.-200ps/nm
D.+200ps/nm
E.+600ps/nm