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

Action Reasoning:
The block 'b' is held in the hand, and block 'c' is clear and on the table, which allows us to stack 'b' on 'c', aligning with the goal state where 'b' should be on top of 'c'.

New State Description:
Block 'b' is on top of block 'c', and block 'c' is supporting block 'b'. The hand is empty. Block 'a' is on top of block 'd', and block 'd' is supporting block 'a'. All blocks are in their goal positions.

Action Chosen:
stack(b, c)
