Answer:
I think it's more man-made possibly, but it might be both. You might want to see if someone says both, both I guess C maybe.
Answer is C bc of the fact of diameter
Answer: We have it inside of our bodies
Explanation: Biology
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.