I would say D! Purely because it is looking at the effects of humans (therefore related to topics more geographical).
Hope that helps. :)
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.
It would be the last one.
The concentration of Na+ is greater inside the cell, and the concentration of K+ is greater outside the cell.
The concentrations of Na+ and K+ are both greater outside the cell.
The concentrations of Na+ and K+ are both greater inside the cell.
The concentration of Na+ is greater outside the cell, and the concentration of K+ is greater inside the cell.
