This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T., Subject name: Physiology
In infants, defecation often follows a meal. The cause of colonic contractions in this situation is 
Select and explain. 
A. Gastroileal reflex, B. Enterogastric reflex, C. Increased circulating levels of CCK, D. Gastrocolic- reflex
D: Gastrocolic- reflex
Answer: D: Gastrocolic- reflex 
Explanation: (Gastrocolic reflex) (511- Ganong) (477- Ganong 23rd)* Distention of the stomach by food initiates contactions of the rectum and , frequently a desire to defecate. The response is called the Gastrocolic reflex* Some evidence that it is due an action of gastrin on the colon and is not neurally mediated* When food leaves the stomach, the cecum relaxes and the passage of chyme through the ileocecal valve increases (Gastroileal reflex). This is presumably a vagal reflex.