Parent State ID: 20
State Depth: 7
Action Taken: unstack(c, b)
Action Reasoning: To achieve the goal state, we need block `d` on top of block `b`. Currently, block `c` is on block `b`, so we should remove block `c` first by picking it up. This simplifies the placement of block `d`.
State Description: Block `a` is on the table and clear. Block `b` is on the table and clear. Block `c` is held by the hand and no longer on block `b`. Block `d` is on the table and clear. The hand is holding block `c`.
Action Path: ['unstack(d, a)', 'put-down(d)', 'unstack(a, c)', 'put-down(a)', 'pick-up(d)', 'put-down(d)', 'unstack(c, b)']

INACTIVE REASON: action path invalid: The last action `unstack(c, b)` is invalid because the precondition that `c` is clear was not met. The current state's description and visualization are based on this invalid action, making them inaccurate.
