This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Pharmacology
The concentration of sodium ions in the standard WHO oral rehydration solutions is: 
Select and explain. 
A. 40m moles/L, B. 60 m moles/L, C. 90m moles/L, D. 110 m moles/L
C: 90m moles/L
Answer: C: 90m moles/L 
Explanation: (Ref: KDT 6/e p658, 659) Concentraton of Na+ is 90m mole/L in standard WHO-ORS whereas it is 75 m mole/L in New formula ORS