Answer:
Natural selection
Explanation:
Natural selection occurs when one allele (or combination of alleles of different genes) makes an organism more or less fit, that it is able to survive and reproduce in a given environment. If an allele reduces fitness, its frequency will tend to drop from one generation to the next.
A true-breeding<span> organism, sometimes also called a purebred, is an organism that always passes down certain phenotypic traits (i.e. physically expressed traits) to its offspring.</span>
heart, arteries, and veins
I will go with choice (C) density dependent pattern
