This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Micronutrient Mineral Deficiencies, Subject name: Pediatrics
Keshan disease is due to deficiency of? 
Select and explain. 
A. Selenium, B. Chromium, C. Zinc, D. Iodine
A: Selenium
Answer: A: Selenium 
Explanation: Ans (a) Selenium