I say E!
Oh wait…
Before I get back to thinking about it I’ll be very disappointed if the answer hinges on that since it was in no way stated or even implied in the problem.
Hang on, doesn’t that mean my answer was exactly right? C can see a white hat, he knows D cannot see two white hats or D would call out black, therefore he knows his own hat is black?
EDIT: Ah, you wrote your reply before I edited my post to add my reasoning, and I didn’t update the thread and see your post until afterwards. 
Try reading the last paragraph again 
“There are no outside influences nor other ways of communicating. They cannot move and are buried in a straight line. So A & B can only see their respective sides of the brick wall, C can see B and D can see B & C.”
I don’t see anything to change my reasoning, and there’s still no implication of them knowing their configuration, since they can’t communicate it to each other and no-one can tell them.
Ah ok, I see where you’re coming from then. You do have the wrong idea though, the solution depends on them knowing where the others are. You were very close with your original post though.
If they know where the others are then I can’t see anything wrong with my reasoning for C. Could you at least tell me why I’m wrong?
Having just seen your edit, I now award you 1 Internet for getting it right. Congrats!
The answer’s C? Hey I was close 
!
Hahaha, I’ve been right for some time and you’ve had me convinced I was missing something!
See, this is why I hate the stupid “no double posting” rule - I always miss edits 
It’s my fault for making my posts a work in progress, really. I’ve on occasion edited a post I made four or five times as I think about it after the fact, I shouldn’t post so quickly.
The black hat in the middle of the two white hats knows that if he had the same color hat as the white hatted he’s looking at, then the white hatted behind him would know right away that HIS hat is black because there’d only be two black hats left, THEREFORE he knows that he must have a black hat.
If they both had white or both had black hats, the guy who sees the two of them would instantly call out the color of his hat, knowing there’s only two other hats which would be the same color as well.
C.
Note: I personally didn’t come to this conclusion, but when I heard it, it makes perfect sense to me.
That’s what I just said, only I put it better. 
You think box office takings reflect how good a movie is?
Hahaha…
HAHAHAHAHAHA
Yeah, by that logic, watchmen is a fucking horrible movie, right up there with plan 9 from other space.
But it was!
What did you say!
guise somebody accidentally the ctrl+v-thread O_0
I liked that one.
