When we are born as babies, we are most attracted to the contrast of black and white images during those first few weeks. More so than color. It seems this primal preference and fascination follows us all into adulthood.
Black and white photos will always be classic. Black and white photos generally, for the most part, will make anyone pause to appreciate the image. It's definitely something that can bring any two people a bit closer, no matter the difference in culture, country, language barrier, etc.
What an excellent idea for a challenge! I like the picture you posted here, I'll have to check out your other posts, too. Thanks for sharing! :)