The immune system choose one:
a. is nonspecific in its responses to invaders.
b. is composed entirely of cells, rather than tissues and organs.
c. kills all nonself cells.
d. is a system that differentiates self from nonself to neutralize harmful invaders.

The correct answer is D. is a system that differentiates self from nonself to neutralize harmful invaders.

Explanation:

A defense system that protects the host body from pathogen infection is called the immune system. This immune system is made up of many different barriers which helps in preventing illness from pathogen attack.

Physical and chemical barriers provide the first line of defense to the body for example skin, mucous membrane, lysozyme in saliva provide first line of defence. Second line of defense is provided by non-specific immune cells like mast cells, macrophages, dendritic cells, etc.

The third line of defense is provided by pathogen-specific immune cells like T lymphocytes and B lymphocytes. These cells have the ability to differentiate self and non-self cell and kills the non-self cell that come from outside the body.

for example, no new evidence will demonstrate that the earth does not orbit around the sun (heliocentric theory), or that living things are not made of cells (cell theory), that matter is not composed of atoms, or that the surface of the earth is not divided into solid plates that have moved over geological timescales .

bacteria could be both, harmful and to us. harmful bacteria could make us sick and probably even by getting the chances of getting a disease, but good bacteria fight it off with your immune system. there is always bacteria everywhere we go. we need to make sure to wash our hands after using the restroom, before eating, after eating, after petting an animal too. so you see, bacteria is everywhere and is harmful or . i hope this . : ) : ) : )