Attempt Number: 2
Error Message: Action not unique compared to other actions chosen from this state before. Choose a new action

Action Reasoning:
To get block C on block A, we need to first clear block A by unstacking it from block B.

New State Description:
Block a is on the table and clear, 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 holding block a.

Action Chosen:
unstack(a, b)
