is this a black and white photo?

Yes... I dont think it says anywhere that b&w is not allowed ? Having said that the image was already pretty much b&w when I took the shot, I just added a b&w because it looked a bit better... Thanks fir the comment friiskiwi

Yes, but then only a color photo can help bring out and emphasize the black part or parts in an image. In this image, author, we can hardly tell which is black, and which is not, at least in my opinion.

"as long as the color black is the main color." If there is no colour in the photo, then how can we tell what is the main colour, even though it isn't stated that B/W aren't allowed I think it's pretty obvious that they want colour photographs.

I don't know then... Let the mods decide