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