Attempt Number: 4
Error Message: Action not unique compared to other actions chosen from this state before. Choose a new action

Action Reasoning:
Block 'd' needs to be placed on top of block 'a' to achieve the goal state. First, I will pick up block 'd' to position it for stacking.

New State Description:
The hand is holding block 'd'. Block 'a' is clear and on top of block 'c'. Block 'b' is clear and on the table. Block 'c' is not clear and on the table. Block 'd' is in hand and not on the table.

Action Chosen:
pick-up(d)
