lol! The missing "submit" and only a "reset" button also drove me nuts!!! That page actually does some javascript code, which is not currently working. (you can see this when you click on one of the options while in console/devtools).
Oh, ha! Awesome! I was killing time on my phone, without full debug options, and from the looks of the site, I figured maybe they were being extra cute.
Its a ruse, they just want you to look at random people's backside and think that it's a elbow. The modern day version of scanning your ass and printing it lol
From the source: false, true, true, false, true, true, false, false, true, true, true, false, true, false (go left to right, top to bottom)
False & true aren't great terms to use for an "either or" question.
This translates to:
(A) (B)
1. elbow, ass;
2. ass, elbow;
3. ass, ass;
4. elbow, elbow;
5. ass, ass;
6. ass, elbow;
7. ass, elbow;