I have an origin-centred, axis-aligned cube. Which of the following could be normal vectors at its corners?
A. $(1,0,0)$
B. $(-1,-1,-1)$
C. $(1,1,-1)$
D. $(1,1,1)$
E. $(0,1,1)$
I tried to calculate every possible normal and I got that A could be the normal. However, I think that multiple answers are correct and I do not know how to check if other answers are valid. Is there any rule to check it?