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: Physiology
Maximum potassium ions secretion is seen in which of the following secretion? 
Select and explain. 
A. Saliva, B. Gastric secretions, C. Jejunal secretions, D. Colonic secretions
A: Saliva
Answer: A: Saliva 
Explanation: Saliva contains large quantity of potassium and bicarbonate ions. The concentration of potassium ion is about 30 mEq/L, seven times as great as in plasma. The concentration of potassium is gastric secretions is relatively low. Colon secretes only a small amount of potassium. Ref: Guyton, 11th Ed Page 794