Parent State ID: 31
State Depth: 7
Action Taken: unstack(a, d)
Action Reasoning: To achieve the goal state, block 'b' needs to be on top of block 'c'. Since block 'c' is already clear and on the table, the next step is to unstack block 'a' from block 'd' to make block 'd' clear and on the table.
State Description: Block 'a' is now held in the hand, block 'd' is clear and on the table, block 'c' is on top of block 'b', and block 'b' is supporting block 'c'. The hand is no longer empty.
Action Path: ['unstack(d, a)', 'put-down(d)', 'pick-up(a)', 'stack(a, d)', 'unstack(c, b)', 'stack(c, b)', 'unstack(a, d)']
