Who can answer this question if you know this one because I am confused on this one

A

Explanation:

With the increase in pollution, the barks started getting darker. The grey squirrels were easily noticed by their predators against this dark background, so they were eaten.

Due to a random mutation, the black fur was acquired. Squirrels with black fur are now more able to camouflage and are less likely to be seen by predators. Those squirrels have a selective advantage, will be able to survive to mating age and pass on those successful alleles to the next generations. The number of grey squirrels (selective disadvantage) will decrease.

Those squirrels can be used to indicate the level of pollution a city is facing. The more pollution there is, the more the black squirrels will be. If efforts are being made to reduce the levels of pollution, the numbers of grey squirrels should increase and that of the black squirrels should decrease.

b

is correct hope this   also i learnd this in middle school

4.) metal

"-the movement of carbon from the nonliving environment into living things and back to the environment

-carbon is the essential component of proteins, fats, and carbohydrates (which make up all organisms)

-carbon exists in air, water, and living organisms

-producers convert carbon dioxide in the atmosphere into carbohydrates during photosynthesis

-bacteria in the atmosphere cycles through the system in filtration units

-in cellular respiration, carbon is released back into the atmosphere as carbon dioxide

-some carbon is stored in limestone (forming one of the largest "carbon sinks" on earth)

-largest carbon reservoir on earth= limestone

-carbon stored in the bodies of organisms as fat, oils, or other molecules may be released into the soil or air when the organism dies

-this may form deposits of coal, oil, or natural gas (fossil fuels, which increased the atmospheric carbon dioxide)

-fossil fuels store carbon left over from bodies of organisms that died millions of years ago

-they are located in the surface of earth, deep within the earth and beneath the ocean floor."