Attempt Number: 3
Error Message: Action not unique compared to other actions chosen from this state before. Choose a new action

Action Reasoning:
We need to put down block `b` onto block `c` to match the goal state. Since block `b` is currently held, the best action is to `stack` block `b` onto block `c` as `c` is clear.

New State Description:
Block `a` is on block `d` and clear. Block `b` is on block `c` and clear. Block `c` is on the table and supporting block `b`. Block `d` is on the table and supporting block `a`. The hand is empty.

Action Chosen:
stack(b c)
