This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gastrointestinal System, Subject name: Physiology
Enterochromaffin Cells in GIT secrete 
Select and explain. 
A. Serotonin, B. Histamine, C. Both, D. None
C: Both
Answer: C: Both 
Explanation: More than 15 types of hormone-secreting enteroendocrine cells have been identified in the mucosa of the stomach, small intestine, and colon. Many of these secrete only one hormone and are identified by letters (G cells, S cells, etc). Others manufacture Serotonin or Histamine and are called enterochromaffin or ECL cells.