Truly no matter if someone doesn't understand after that its up to other people that they will help, so here it occurs.
It would be my guess that this painting was painted the "A" way up and that's probably why I am voting for that way up. However, the "B" way up is still an acceptable visual experienced for me - despite that it looks (to me) upside down. But if the artist wants to disturb the viewer slightly (and should art not challenge pre-conceived ideas also?) it might have a stronger more longer lasting effect to leave it "B" side up. In the end it must all depend on what the artist's FINAL intentions are - and - that intention might be to disturb as one visually pleases.