Your answer would be: New traits, lose. This is because evolution is when a species changed and adapts to changes in their environment. During this process, they may lose old traits that are no longer useful.
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.
Carnivores. Herbivores, on the other hand, prey on plants.
The human digestive system can fail if you eat something harmful, and it can break down nutrients, techinically the digestive system can stop working if you get something like Gastoparesis, which stops the movement of food through the digestive system.
