Which situation would affect an organism's niche in a positive way?

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Explanation:

Niche construction is the process by which an organism alters its own (or another species') local environment. These alterations can be a physical change to the organism's environment or encompass when an organism actively moves from one habitat to another to experience a different environment.

answer; i do believe that the correct answer is; ///mendelian genes are at specific loci on the chromosome and, in turn, segregate during meiosis;

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.