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.
The organisms that create all the usable food energy on Earth are called the producers. These organisms are able to produce food through the different resources such as the energy from the Sun, the carbon dioxide, and water and minerals that they absorb from the soil
The fight or flight system is a reaction that the body undergoes when put in an either stressful or frightening situation. It includes both the nervous and endocrine system.
The sympathetic division of the peripheral nervous system is used in this response as the sympathetic nervous system works up the body, increases the rate of breathing, heart rate, dilates the pupils, produce more sweat and slow the digestion rate. This reaction happens in the flight or fight system.
Answer:A
Explanation:it makes sense
The surviving R strain transformed into a living S strain.