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: Social & Preventive Medicine
Which ion is added in OPV vaccine acts as stabilizer 
Select and explain. 
A. Sodium, B. Magnesium, C. Chloride, D. Potassium
B: Magnesium
Answer: B: Magnesium 
Explanation: None