Attempt Number: 2
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 stack block 'd' on top of block 'a'. Currently, both blocks are clear and the hand is empty. The best next action is to pick up block 'd'.

New State Description:
The hand is holding block 'd'. Block 'a' is on top of block 'c' and clear. Block 'b' is clear and on the table. Block 'c' is not clear and on the table. Block 'd' is no longer clear, and it is being held by the hand.

Action Chosen:
pick-up(d)
