Attempt Number: 3
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, we need to have block 'd' on top of block 'c'. Currently, block 'd' is held in the hand, and block 'c' is clear and on the table. Therefore, we should put down block 'd' on top of block 'c'.

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

Action Chosen:
stack(d, c)
