Answer:
Explanation:
Artificial selection is the process by which humans choose individual organisms with certain phenotypic trait values for breeding. If there is additive genetic variance for the selected trait, it will respond to the selection, that is, the trait will evolve.
The correct answer is 20% on average. The ideal percentage rate of a healthy man with normal weight is 18 to 22%. However, a range of 7-13% is considered normal for male professional athletes, because their muscular mass is much greater. The physiological minimum rate which is acceptable for males is 4-6%.
The right answer is D (less responsive to antigens)
It is proven that, after puberty, thymus activity (an organ that is included in the lymphatic system, producing T cells that pick up antigens) decreases and that in adult and aged people the thymus has no role. Work done in humans indicate that in fact the cellularity begins to decline from birth in favor of lymphocyte perivascular spaces and connective and adipose tissue, which leads to a decrease in the capture of antigens.
