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
Normal gastric juice contains all except 
Select and explain. 
A. Na+, B. K+, C. Ca++, D. Mg++
C: Ca++
Answer: C: Ca++ 
Explanation: Contents of gastric juice
-        Cations

Na+
K+
Mg+2
H+

-        Anions

Cl-
PO4-2
SO4-2

-        Pepsin
-        Gastric lipase
-        Mucus
-        Intrinsic factor of Castle