<prompt> What is the most common cause of gastric outlet obstruction in a 4-week-old babyAnnular pancreasForeign bodyCongenital hyperophic pyloric stenosisDuodenel atresia  <response>: It is seen between 3rd and 6 the week of age of an infant because it;s the time taken by the hyperophied muscle to cause complete obstruction. SRB edition 5th page no: 821 