Parent State ID: 9
State Depth: 3
Action Taken: pick-up(block_d)
Action Reasoning: Block D needs to be placed on Block C to approach the goal state. The hand is empty, and Block D is clear, so the next best action is to pick up Block D.
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 as it supports block B. Block D is held in the hand and not clear. The hand is not empty.
Action Path: ['unstack(block_b, block_c)', 'stack(block_b, block_c)', 'pick-up(block_d)']

INACTIVE REASON: action path invalid: The last action, pick-up(block_d), is invalid because its preconditions are not met: block_d is not clear, block_d is not on the table, and the hand is not empty before the action. The current state's description and visualization are accurate, but the action itself is not logical.
