There are three blocks. Lets call them A, B and C. Block B is below C and block A is below B. Block A contains a medium black square. Block B contains a medium black square, a medium blue square and a big blue triangle. This block also has a big yellow square. Below the big yellow square and the big blue triangle is the medium black square. The medium blue square is above the big blue triangle and the big yellow square. Block C contains one big black triangle.
What is below the big black triangle? a medium black square or a medium blue square?
medium black square  medium blue square  both of them none of them