There are three blocks, A, B and C. Block C is above and A is below B. Block A contains a medium blue square and one medium yellow square. A medium black square is below the medium blue square and the medium yellow square. Below the medium yellow square is the medium blue square. Block B contains one medium yellow square. And block C has a medium black square.
Which object is above a medium black square? the medium yellow square that is in block B or the medium yellow square that is in block A?
the medium yellow square  that is in block B the medium yellow square  that is in block A both of them none of them