Which best describes evolution?

A. It is a theory backed up by scientific evidence.

B. It is guess about how organisms change.

C. It is a hypothesis that is not supported by scientific evidence.

D. It is a hunch that animals change over time

A. It is a theory backed up by scientific evidence.

Explanation:

Charles Darwin had written a book called "On the Origins of Species" in 1859. It was based on the theory of evolution through natural selection. Evolution by natural selection is one of the best substantiated theories in the history of science, supported by evidence from a wide variety of scientific disciplines, including paleontology, geology, genetics and developmental biology.

it has to be understood that the sea water contains a huge amount of sodium and chlorine ions and if they enter the cell of the atlantic cod fish, the cell will shrivel and the fish will die. to avoid such a condition, the fish uses active transport for the purpose of removing the ions against the gradient.

explanation:

the atlantic cod is not a maritime osmoconformer. its native application of salts is less than that of the seawater it lives in. it is continually falling water from the gills to the ocean via osmosis.

countering that, the fish is going to be swallowing seawater. but since its internal collection of salts is lower than seawater, the fish will want to go free of excess salt, and since that's going upon a gradient, then active transport, requiring energy, must be used to pump out the salt. much marine fish use the organs to filter out the salt and these fish discharge very straight urine.