This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: RDA, Nutritional Requirements, Subject name: Social & Preventive Medicine
'Twin foified salt' contains: 
Select and explain. 
A. Iodine + Fluorine, B. Iodine + Calcium, C. Iodine + Iron, D. Iodine + Chlorine
C: Iodine + Iron
Answer: C: Iodine + Iron 
Explanation: National Institute of Nutrition (Hyderabad) developed 'Twin Foified Salt' also known as 'Double Foified Salt' (DFS) to prevent iron & iodine deficiencies. DFS - contains Iron and Iodine contains salt, Potassium Iodinate, Ferrous sulphate and sodium hexa metaphosphate. provides 40 mcg Iodine and 1 mg Iron per gram of salt.