The option which is not a potential hazard to your head is A. dust. Dust
is pretty harmless, so I don't see how it can hurt your head, unless
you are allergic to it, and inhale it, and then it can hurt your whole
body, not just your head. Electrical shock, falling objects, and low
hanging beams can provide pain to your head if you hit these objects or
get shocked by electrics.
