There are two blocks. Lets call them A and B. Block A has a medium yellow square. A medium blue square is touching the bottom edge of this block. A medium black square is below the medium yellow square. The medium blue square is below the medium yellow square and the medium black square. Below block A we have block B which contains two medium blue squares. Below medium blue square number two there is medium blue square number one.
What is below the black thing? a yellow thing or a medium blue square that is touching the bottom edge of a block?
yellow thing medium blue square  that is touching the bottom edge of a block  both of them none of them