Also the fact that you needed to click EXACTLY on the radio button (wasting all that space that the td > input[type=radio] occupies) and that it doesn't show a cursor: pointer; when hovering on the (<) Previous and Next (>) buttons.

Funny quiz nonetheless. I'm an avid fan of Science (Astronomy, Astrophysics, Biology and Cosmology.), but I didn't get most of the questions right. /sigh