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
[{'content': 'The concentration of sodium ions in the standard WHO oral rehydration solutions is: \nSelect and explain. \nA. 40m moles/L, B. 60 m moles/L, C. 90m moles/L, D. 110 m moles/L', 'role': 'user'}, {'content': 'Answer: C \nExplanation: (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', 'role': 'assistant'}]