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

Action Reasoning:
The best next action is to unstack block B from block C. This clears block C so that block D can be stacked on it as needed for the goal configuration.

New State Description:
Block A is on the table and is still clear. Block B is now held by the hand and is no longer clear. Block C is on the table and is now clear. Block D is on the table and remains clear. The hand is holding block B.

Action Chosen:
unstack(block_b, block_c)
