Evolutionary biology is the study of

Evolutionary biology is the study of the adaptions and changes that occur and occurred in organisms and how these are related to the diversity of species we have to day.

Hope it helped,

BioTeacher101

(If you have any questions, feel free to ask them in the comments)

b - the respond is innate and varies over time.

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genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).