Attempt Number: 4
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 where Block C is on Block B, we need to stack Block C onto Block B. First, we must pick up Block C, as it is already clear and on the table.

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

Action Chosen:
pick-up(c)
