(A)
- Stack with blue block
- Stack with orange block
- Stack with red block

(B)
- Stack with purple block
- Stack with yellow block, red block, from bottom to top

(C)
- Stack with red block, blue block, orange block, from bottom to top

(D)
- Stack with red block
- Stack with green block
- Stack with purple block
- Stack with orange block
- Stack with blue block