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 yellow square? the medium black square that is in block B or the medium black square that is in block A?
the medium black square  that is in block B the medium black square  that is in block A both of them none of them