Discussing this with some friends, it was suggested that the correct choice is. 5, ie. bottom row in the middle. because. the puzzle is a form of simple addition.
The answer could also be E for the last one since because each row has in total then (of the rectangle) two tops, one bottom and one left and one right. This is why iq tests often annoy me because you can have a logically consistent answer and still be wrong.
Answer 2 gives +3 IQ Puzzle 31: People claim that answer 4 gives them more IQ but nobody seem to be able to give a nice explanation for it, other people agree with me that answer 2 gives more IQ and i have retaken the test 6 times where i answered 14 right, 1 wrong and 1 of each answer of puzzle 31 which only lead to answer 2 giving more IQ