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: Pediatrics
[{'content': 'Microcephaly is defined as \nSelect and explain. \nA. Head circumference < -3SD below the mean for age and sex, B. Head circumference < -2SD below the mean for age and sex, C. Head circumference below 10th percentile the mean for age and sex, D. Head circumference below 15th percentile the mean for age and sex', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Macrocephaly : Head circumference > 2SD above the mean for age and sex', 'role': 'assistant'}]