Parent State ID: 25
State Depth: 6
Action Taken: stack(a, d)
Action Reasoning: The goal is to place block 'a' on top of block 'd'. Since block 'a' is currently held and block 'd' is clear, the best action is to stack 'a' on 'd'.
State Description: Block 'a' is on top of block 'd', and both blocks 'b' and 'c' remain clear and on the table. The hand is now empty. In the diagram, block 'a' is stacked on block 'd', and the hand is no longer holding anything.
Action Path: ['unstack(c, b)', 'put-down(c)', 'unstack(d, a)', 'put-down(d)', 'pick-up(a)', 'stack(a, d)']
