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

Action Reasoning:
The current state requires block `c` to be placed on the table so that block `b` can be stacked on it, matching the goal. We first perform `put-down(c)` to free the hand for the next stacking.

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

Action Chosen:
put-down(c)
