This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Highest concentration of potassium is seen in ? 
Select and explain. 
A. Jejunum, B. ileum, C. Duodenum, D. Colon
D: Colon
Answer: D: Colon 
Explanation: Ans. is 'd' i.e., Colon