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

Action Reasoning:
To reach the goal state, block 'a' should be stacked on block 'c'. Since all preconditions are met, the next best action is to stack 'a' on top of 'c'. This places 'a' in the correct position according to the goal.

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

Action Chosen:
stack(a, c)
