Parent State ID: 1
State Depth: 2
Action Taken: unstack(blockB, blockC)
Action Reasoning: The goal is to get block D on top of block C. Since block C is not clear because it supports block B, the first step is to unstack block B from block C.
State Description: Block A is on the table and clear. Block B is in the hand and no longer on block C. Block C is on the table and now clear. Block D is still held in the hand. The hand is holding block B.
Action Path: ['pick-up(blockD)', 'unstack(blockB, blockC)']

INACTIVE REASON: deactivated because diagram generation failed or invalid action chosen: The hand is not empty, violating the precondition for unstacking.
