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: Unknown
[{'content': 'Chignon is: \nSelect and explain. \nA. Cephal hematoma, B. Artificial caput, C. Scalp laceration, D. Excessive moulding', 'role': 'user'}, {'content': 'Answer: B \nExplanation: A vacuum is applied (usually 0.2 kg/cm2 for vacuum extraction of a baby).\nThe scalp is sucked into the cup and an artificial caput is produced. This chignon usually disappears in a few hours.', 'role': 'assistant'}]