单项选择题

洞口防护措施中边长()的洞口需满铺模板或脚手板固定封闭严密,模板或脚手板与洞口边缘间距不得大于()。

A.0.5m~1.5m,30mm
B.0.5m~1.5m,50mm
C.25mm~0.5m,30mm
D.25mm~0.5m,50mm