might as well do sth固定搭配 最好做某事,

it is useless to argue with him 跟他争论是没用的
you might just as well go to the seaside to argue with the sea你还不如去海边跟大海争论

所以选A

若有疑问及时追问,满意敬请采纳,O(∩_∩)O谢谢~~