Parent State ID: 17
State Depth: 4
Action Taken: put-down(block_d)
Action Reasoning: We should put block D down onto the table. This will make the hand free to pick up other blocks and ultimately allows for the stacking of blocks in the correct sequence to reach the goal.
State Description: Block A is on the table and clear. Block B is on block C and clear. Block C is on the table and not clear. Block D is on the table and clear. The hand is empty.
Action Path: ['unstack(block_b, block_c)', 'stack(block_b, block_c)', 'pick-up(block_d)', 'put-down(block_d)']

INACTIVE REASON: action path invalid: The last action (put-down(block_d)) is valid in terms of preconditions and effects, but it does not progress towards the goal state. The current state's natural language description and visualization are accurate, but the action sequence does not logically move towards achieving the goal.
