What strategy involves the use of nutrients to directly encourage the growth of existing healthy biota

i think it is d. objects resist changes in their state of motion.

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 . : ) : ) : )

i think the answer is a.keratin is the pigment responsible for skin color.