You will your on this certain day hope this helped
I believe that the answer is chemical change
The answer is letter A.
In the evolutionary sense fitness refers to the measure of reproductive success of an individual or of organisms in general. Those organisms that leave the largest number of mature offspring are the fittest. Fitness can be achieved through survival or mortality selection, mating success or sexual selection, and family size or fecundity selection. Fitness is critical for a species’ survival and is a major adaptation that all organisms do through a long period of time.
Integumentary system
EXPLANATION: Defends the body after it has been invaded by a microscopic organism. Integumentary system. Protects the internal tissues of the body from potential harm.