Keshan disease caused by-

Ans. is 'a' i.e., Selenium* Keshan's disease is a form of cardiomyopathy and is characterized by multifocal myocardial necrosis, cardiac arrhythmias and cardiac enlargement.* It is prevalent in the Keshan province of China, soil of which is deficient in Selenium.* Selenium deficiency in the soil is found to cause an increased prevalence of highly cirulent coxsackie B virus. Hence selenium deficiency and the superimposed Coxsackie B virus is found to precipitate Keshan's disease.* Treatment is selenium and Vitamin E supplementation