This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Necrotising enterocolitis, Subject name: Pediatrics
[{'content': 'A very preterm baby on 30mL/kg of enteral feeding, using an infant feeding formula, developed sudden severe abdominal distension with visible bowel loops on day 6 of life. The baby also showed temperature instability and lethargy. X-ray of the abdomen showed poal venous gas. The staging of NEC is? \nSelect and explain. \nA. I b, B. 2a, C. 2b, D. 3a', 'role': 'user'}, {'content': "Answer: C \nExplanation: The given clinical scenario indicates a diagnosis of NEC. Salient clinical features helping to identify the stage of NEC are: Stage Feature 1a - Occult blood positive in stool 1b - Fresh blood in stool 2a - Abd X ray shows 'pneumatosis intestinalis' 2b- X ray shows Poal venous gas 3a - Peritonitis 3b - Pneumoperitoneum", 'role': 'assistant'}]