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 logical action is to stack block A on block B because block B is clear, and this will help build the correct order towards the goal state where block A is on block B.

New State Description:
Block A is now on block B and is clear. Block B remains on block D and is not clear. Block C is clear and on the table. Block D is not clear on the table. The hand is empty.

Action Chosen:
stack(block_a, block_b)
