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

Action Reasoning:
Block A is currently held by the hand and needs to be placed on Block B to reach the goal. Since Block B is clear, the best action is to stack Block A on Block B.

New State Description:
Block A is on Block B and is clear. Block B is on Block D and not clear. Block C is on the table and not clear, with Block D stacked on it. Block D is on Block C and not clear. The hand is empty.

Action Chosen:
stack(block_a, block_b)
