Attempt Number: 4
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, we need to put block 'd' on top of block 'c', which is clear. The next best action is to stack 'd' on 'c', as this aligns with the goal and does not violate any preconditions.

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 clear. The hand is empty. The diagram would show block 'a' on block 'b', block 'c' on the table with block 'd' on top of it.

Action Chosen:
stack(d, c)
