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

Action Reasoning:
To achieve the goal state, we need block 'd' on top of block 'c'. Since 'd' is currently held, the best action is to stack 'd' on 'c', which is clear.

New State Description:
Block 'a' is on the table and clear. Block 'c' is on top of block 'b' and is no longer clear. Block 'b' is on the table. Block 'd' is on top of block 'c' and clear. The hand is empty.

Action Chosen:
stack(d, c)
