B!! Because it talks more about the question
Answer: A. Average rainfall has decreased
Explanation:
I might be wrong. sorry if i'm wrong
Genetic drift I believe because it means <span>variation in the relative frequency of different genotypes in a
small population, owing to the chance disappearance of particular genes
as individuals die or do not reproduce.</span>
In the immune response the body reacts to each kind of
pathogen with a defense targeted specifically for that pathogen.
I believe the answer might be A.
I apologize if it’s wrong