Which disorder of the digestive system is due to an absence of nerves (ganglion) in a segment of the colon, usually the sigmoid colon? a. pyloric stenosis b. imperforate anus c. hirschsprung's disease d. esophageal atresia?

The right option is c. Hirschsprung's disease

Hirschsprung disease is a developmental disorder characterized by the absence of ganglia in the distal colon, resulting in a functional obstruction. This disorder may occur by itself or in association with other genetic disorders such as down syndrome. It mostly occurs in babies and young children. The most important symptom is chronic constipation. Other symptoms are vomiting, abdominal pain and diarrhea. Hirschsprung's disease is treated by surgical removal of the abnormal section of the colon, followed by reanastomosis.