Don't play with the knife. It ( ) hurt yourself.

B. might

与may相比， migh的语气更弱，可能性更小，这里根据语境被刀划伤的可能性很小，而且主观上也不愿意，所以选might

might

虚拟语气。

A

may
e.g. Don't play with the sharp knife. It may hurt you.
不要玩那么锋利的刀，有可能伤着你。

might, 虚拟语气。

有可能伤害到你

B. might