单项选择题
Whenoptimizingastandalonepoint－to－multipointbridgeinstallationwitheightnon－rootbridges，whichofthe followingRTSthresholdandCWminsettingswouldbecorrectforthenon－rootbridges？（）
A.RTSthreshold=4000，CWmin=3
B.RTSthreshold=1，CWmin=4
C.RTSthreshold=4000，CWmin=5
D.RTSthreshold=1，CWmin=5