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