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

Action Reasoning:
Since the goal is to place block C on block A, and block C is currently held in the hand, we should stack C on A directly as A is clear and ready to support C.

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

Action Chosen:
stack(c, a)
