Visual IQ puzzle (MENSA Norway, difficulty 3)
Correct answer: C
Explanation: Consider each row from left-to-right or each column from top-to-bottom. Each image has a line in the middle. Third image is obtained adding the previous 2 images. The squares of the same color but on opposite positions relative to he middel line are cancelled out, whereas the squares of the same color that are on the same side of the line are added.