This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fluid and electrolytes, Subject name: Medicine
[{'content': 'The concentration of sodium ion is least in the - \nSelect and explain. \nA. Small intestinal juice, B. Bile, C. Gastric juice, D. Pancreatic juice', 'role': 'user'}, {'content': 'Answer: C \nExplanation: primary gastric juice contains Na+ in a concentration of 3-5 mEq/l makes it possible that the secreted volume originates from some sodium-containing compament Ref Davidson 23rd edition pg 365', 'role': 'assistant'}]