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

Action Reasoning:
To move towards the goal state, first pick up block 'd' so that block 'a' is clear. This allows us to stack 'a' on 'c' in a subsequent step.

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

Action Chosen:
pick-up(d)
