This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nutrition, Subject name: Pediatrics
Keshan disease is caused by deficiency of: 
Select and explain. 
A. Thiamine, B. Zinc, C. Selenium, D. Proteins
C: Selenium
Answer: C: Selenium 
Explanation: Ans. C. Selenium* Selenium is a constituent of glutathione peroxidase, an antioxidant in red blood cells and other tissues.* Glutathione peroxidase scavenges free Hydro peroxidases generated during fatty acid oxidation, thus protecting the cell from damage due to free radical formation.* Severe deficiency is the major cause of Keshan disease, which presents as cardiomyopathy in young children. Skeletal myopathies have also been reported.* Mild deficiency is associated with macrocytosis and loss of hair pigment.