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: Radiology
[{'content': 'Earliest detectable Congenital Malformation by USG is: \nSelect and explain. \nA. Spina bifida, B. Cystic hygroma, C. Anencephaly, D. Encephalocele', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Anencephaly', 'role': 'assistant'}]