What is the spatial relation betweeen the red block and the yellow block?
(A) The red block is directly above the yellow block, and they are in the same stack.
(B) The red block is directly below the yellow block, and they are in the same stack.
(C) The red block and the yellow block are at different stacks.
(D) At least one of the red block and the yellow block does not exist in the presented configurations.