50kg/h钢轨,12号道岔,辙叉前长1849mm,辙叉后长2708mm,辙叉前开口量、后开口量分别为()

50kg/h钢轨,12号道岔,辙叉前长1849mm,辙叉后长2708mm,辙叉前开口量、后开口量分别为()

A.154mm和226mm

B.226mm和154mm

C.171mm和228mm

D.228mm和171mm

正确答案是A