Parent State ID: 59
State Depth: 9
Action Taken: pick-up(block_b)
Action Reasoning: The goal is to build the stack Block C -> Block D -> Block B -> Block A in that order. Block D is already in place on Block C. Next, block B, which is clear and on the table, should be picked up so it can be stacked on Block D.
State Description: Block A is on the table and clear. Block B is held by the hand. Block C is on the table and supporting block D. Block D is on block C and clear. The hand is holding Block B.
Action Path: ['unstack(block_b, block_c)', 'stack(block_b, block_d)', 'unstack(block_b, block_d)', 'stack(block_b, block_d)', 'unstack(block_b, block_d)', 'put-down(block_b)', 'pick-up(block_d)', 'stack(block_d, block_c)', 'pick-up(block_b)']

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