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 'a' on top of block 'b' and block 'd' on top of block 'c'. The next logical step is to unstack block 'd' from block 'c' so that we can move block 'c' to the table.

New State Description:
Block 'a' is on the table and clear. Block 'c' is on top of block 'b' and clear. Block 'b' is on the table. Block 'd' is held in the hand. The hand is not empty.

Action Chosen:
unstack(d, c)
