Attempt Number: 2
Error Message: Action not unique compared to other actions chosen from this state before. Choose a new action

Action Reasoning:
The next action should place block B onto block D, which is on the path towards achieving the goal state, where B needs to be under A. Placing B onto D will set up the correct stack order for subsequent actions.

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. The hand is empty.

Action Chosen:
stack(block_b, block_d)
