Parent State ID: 61
State Depth: 10
Action Taken: stack(block_d, block_c)
Action Reasoning: Block D needs to be placed on block C to begin forming the stack. Since block C is clear and on the table, we can stack block D on block C. This will help us build the stack towards the goal state.
State Description: Block A is on the table and clear. Block B is on the table and clear. Block C is on the table and not clear as block D is on it. Block D is on block C and clear. The hand is empty.
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)', 'stack(block_b, block_c)', 'unstack(block_b, block_c)', 'put-down(block_b)', 'pick-up(block_d)', 'stack(block_d, block_c)']

INACTIVE REASON: action path invalid: The last action `stack(block_d, block_c)` is invalid because the precondition that `block_c` must be clear is not met. `block_d` is already on `block_c`, making `block_c` not clear. Therefore, the current state's natural language description and visualization are not valid.
