[{"from": "human", "value": "Design a molecule that meets the criteria outlined in the description. The molecule is an octadecatetraenoic acid containing a conjugated system of double bonds at positions 9, 11, 13 and 15."}, {"from": "gpt", "value": "[C][C][C][=C][C][=C][C][=C][C][=C][C][C][C][C][C][C][C][C][=Branch1][C][=O][O]"}]