This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Mesentry, neurovascular bundle, Subject name: Anatomy
[{'content': 'A 6-year-old girl comes to her pediatrician with constipation, abdominal distention, and vomiting. After thorough examination, she is diagnosed as having Hirschsprung disease (aganglionic megacolon), which is a congenital disease and leads to dilation of the colon. This condition is caused by an absence of which of the following kinds of neural cell bodies? \nSelect and explain. \nA. Sympathetic preganglionic neuron cell bodies, B. Sympathetic postganglionic neuron cell bodies, C. Parasympathetic preganglionic neuron cell bodies, D. Parasympathetic postganglionic neuron cell bodies', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Aganglionic megacolon (Hirschsprung disease) is caused by the absence of enteric ganglia (parasympathetic postganglionic neuron cell bodies) in the lower pa of the colon, which leads to dilatation of the colon proximal to the inactive segment, resulting in an inability to evacuate the bowels. The other neuron cell bodies listed are not involved in this condition.', 'role': 'assistant'}]