A Chinese child with cardiomyopathy was diagnosed to have Keshan disease. Deficiency of which of the following results in Keshan disease?

Selenium deficiency result in congestive cardiomyopathy and the condition called Keshan disease. Keshan disease is an endemic cardiomyopathy prevalent in China where selenium contents in crops and and soil are extremely low. Zinc deficiency results in anemia, growth retardation, gonadal atrophy, diarrhea and skin rashes. Copper deficiency results in anemia, neutropenia, osteoporosis, neurologic abnormalities caused by demyelination and faulty synthesis of neurotransmitters. Magnesium deficiency results in tetany similar to that seen with hypocalcemia. Ref: Chandrasoma P., Taylor C.R. (1998). Chapter 10. Nutritional Diseases. In P. Chandrasoma, C.R. Taylor (Eds), Concise Pathology, 3e.