Attempt Number: 4
Error Message: Action not unique compared to other actions chosen from this state before. Choose a new action

Action Reasoning:
Stack block B onto block D to progress toward building the goal stack, as both block D and the hand with block B are clear for this action.

New State Description:
Block A is on the table and clear. Block B is on block D and clear. Block C is on the table and clear. Block D is on the table and not clear since block B is on top of it. The hand is empty.

Action Chosen:
stack(block_b, block_d)
