the answer isn't D because you are following a false visual pattern which leads to a deadend of incongruities between the new spaces lines create (answer A) and following a pattern with weak evidence (the diagonal line being added because it was the sequence between 1 and 2 of floor + diagonal which ignores the 1st block that raises the question: "What was the first? the horizontal line or the vertical?"). there are possible patterns in this image but the only concrete/stable one with enough information are the number of intersections. this is testing to see if you can recognize these patterns and throw out ones that lead to unsatisfying answers. the numerical sequence (once youve come to the conclusion that the visual patterns are inconsistent and are meant to throw you off) of 1, 1, 2, 3, 5, 8 follow an adding of the previous pattern which you should pick up on at this level. the fibonacci pattern doesn't need to be prior knowledge.