<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:An 8-month-old boy is brought to a medical office by his mother. The mother states that the boy has been very fussy and has not been feeding recently. The mother thinks the baby has been gaining weight despite not feeding well. The boy was delivered vaginally at 39 weeks gestation without complications. On physical examination, the boy is noted to be crying in his mothers arms. There is no evidence of cyanosis, and the cardiac examination is within normal limits. The crying intensifies when the abdomen is palpated. The abdomen is distended with tympany in the left lower quadrant. You suspect a condition caused by the failure of specialized cells to migrate. What is the most likely diagnosis?? A: Meckel diverticulum, B: DiGeorge syndrome, C: Pyloric stenosis, D: Duodenal atresia, E: Hirschsprung disease,  <response>: Based on the information provided in the question stem, this is likely a case of a condition caused by the failure of specialized cells to migrate in an 8-month-old boy presenting with fussiness, poor feeding, weight gain despite poor feeding, crying when abdomen is palpated, and abdominal distension with tympany in the left lower quadrant. The choices provided include various gastrointestinal abnormalities. Meckel diverticulum and duodenal atresia can cause obstruction but are less likely in an 8-month-old. DiGeorge syndrome is caused by a chromosomal deletion rather than failure of cell migration. Pyloric stenosis and Hirschsprung disease are both caused by the failure of specialized cells to migrate properly during fetal development. Pyloric stenosis typically presents earlier, around 2-8 weeks of age, with projectile vomiting as the hallmark symptom. Hirschsprung disease presents later, often after the newborn period, with abdominal distension, constipation, and failure to pass meconium due to the lack of ganglion cells in the colon. This fits best with the clinical presentation in the question stem.E: Hirschsprung disease 