This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
[{'content': 'In hydrops foetalis, on ultrasonography, the earliest sign is the development of foetal : \nSelect and explain. \nA. Pericardial effusion, B. Ascites, C. Pleural effusion, D. Skin edema', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Skin edema', 'role': 'assistant'}]