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, I need to place block "a", currently held by the hand, on block "d", which is clear on the table.

New State Description:
Block `b` is on the table, supporting block `c`. Block `c` is clear on top of block `b`. Block `a` is now on top of block `d` and is clear. Block `d` is on the table and is not clear because it supports block `a`. The hand is empty.

Action Chosen:
stack(a, d)
