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

Action Reasoning:
The goal is to have block 'd' on block 'b'. Since block 'c' is currently on block 'b', the next best action is to put block 'c' onto the table, which will free block 'b' for block 'd' to be stacked on later.

New State Description:
Block 'a' is on block 'd' and is clear. Block 'd' is on the table and is not clear since block 'a' is on it. Block 'c' is now in the hand, having been removed from block 'b'. Block 'b' is on the table and is clear. The hand is holding block 'c'.

Action Chosen:
unstack(c, b)
