There are three blocks, A, B and C. Block A has a small yellow square. Below and to the left of the small yellow square there is a medium blue circle. Then, there is block B with a big black triangle in it. Finally, we have block C which is below both blocks B and A. It contains a medium black circle. The medium black circle is below a medium blue square.
What is above the medium blue square? a medium black circle or a small yellow square?
medium black circle  small yellow square  both of them none of them