This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Amniotic Fluid Dynamics, Subject name: Gynaecology & Obstetrics
[{'content': 'All are causes of Polyhydramnios EXCEPT : \nSelect and explain. \nA. Occult spina bifida, B. Diabetes mellitus, C. Swallowing defects in fetus, D. Multiple pregnancy', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Polyhydramnios Causes: Diabetes Twin pregnancy Cleft lip/palate Duodenal atresia Esophageal atresia Neural tube defects Gastroschisis Disorders such as duodenal atresia, esophageal atresia, gastroscisis and diaphragmatic hernia cause swallowing defects Open spina bifida causes polyhydramnios (not occult spina bifida)', 'role': 'assistant'}]