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
Which of the following is the pacemaker of the gastrointestinal tract? 
Select and explain. 
A. P cells, B. Oxyntic cells, C. Interstitial cells of Cajal, D. Parietal cells
C: Interstitial cells of Cajal
Answer: C: Interstitial cells of Cajal 
Explanation: Interstitial cells of Cajal are the pacemaker cells of the GIT that initiate the basic electric rhythm(BER). These are stellate mesenchymal pacemaker cells with smooth muscle-like features. In the stomach and the small intestine, these cells are located in the circular smooth muscle layer near the myenteric plexus. In the colon, they are at the submucosal border of the circular muscle layer. Ref: Ganong&;s review of Medical physiology 26th edition Pgno: 494-495