单项选择题

A.35kV及以下为4m,63kV为5m,110kV为6m
B.35kV及以下为5m,63kV为6m,110kV为8m
C.35kV及以下为5m,63kV为7m,110kV为9m
D.35kV及以下为6m,63kV为8m,110kV为10m