The answer is choice C 50%
HIV tests are used to detect the presence of the human immunodeficiency virus
(HIV) the virus that causes acquired immunodeficiency syndrome (AIDS) in serum, saliva , or urine such tests may antibodies, antigens, or RNA .
Answer: C. there is more silicon than calcium at the surface of the earth
Explanation:
D - an increase in tree cover in the tundra.
