Chinese scientists demonstrated that supplements could prevent keshan disease.
a. zinc
b. selenium
c. manganese
d. copper

Chinese scientists demonstrated that selenium supplements could prevent Keshan disease. The correct answer is B. Keshan disease is actually caused by the deficiency of selenium in an organism, which is why taking selenium supplements is supposed to prevent the disease from happening. Keshan disease is the disease of the heart which may lead to heart failure.

C. which metal is less dense