[{"from": "human", "value": "Design a molecule that meets the criteria outlined in the description. The molecule is an aldehydic acid. It is functionally related to a propionic acid. It is a conjugate acid of a 3-oxopropanoate."}, {"from": "gpt", "value": "[C][Branch1][Ring1][C][=O][C][=Branch1][C][=O][O]"}]