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: Medicine
Keshan disease is an endemic cardiomyopathy found in deficiency of 
Select and explain. 
A. Selenium, B. Manganese, C. Chromium, D. Copper
A: Selenium
Answer: A: Selenium 
Explanation: (Selenium) (410-H) (449-H17th)Keshan disease - found in children and young women residing in regions of china where dietary intake of selenium is low (< 20 mg/d)* Concomitant deficiencies of iodine and selenium may worsen the clinical manifestations of cretinism.