Attempt Number: 2
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 where block 'a' is on top of block 'c', the first step is to pick up block 'a' since it is clear and the hand is empty.

New State Description:
Block 'a' is held in the hand and no longer on the table. Block 'b' is on the table and clear. Block 'c' is on the table and clear. Block 'd' is on the table and clear. The hand is no longer empty and is holding block 'a'.

Action Chosen:
pick-up(block_a)
