单项选择题

A.单面焊接不小于100mm,双面焊接不小于50mm
B.单面焊接不小于100mm,双面焊接不小于55mm
C.单面焊接不小于110mm,双面焊接不小于50mm
D.单面焊接不小于110mm,双面焊接不小于55mm