Attempt Number: 4
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, block `b` should no longer be supporting block `c`. Unstack `c` from `b` to set `c` on the table in the next steps.

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

Action Chosen:
unstack(c b)
