This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Normal Physiology - Sodium, Potassium, and Acid-Base Balance, Subject name: Surgery
Concentration of Na (mEq/I) in normal saline is? 
Select and explain. 
A. 77, B. 109, C. 130, D. 154
D: 154
Answer: D: 154 
Explanation: Ans. (d) 154Ref: Essentials of General Surgery edited by Richard M. Belly Merril T. Dayton p-51 4thed