Ascientific theory is

a. a hypothesis that has been rigorously tested and never been disproven.
b. a hypothesis that has been rigorously tested and only been disproven a few times.
c. an opinion.
d. a hypothesis that has been tested at least five times.
e. an idea based on a person's experience or knowledge.

The correct answer is A. a hypothesis that has been rigorously tested and never been disproven.

Explanation:

A hypothesis is an idea or guess or a proposed explanation of any phenomena. When the hypothesis is checked and proved by many experiments and cannot be disproven by anyone then it considered as a scientific theory.

Therefore a scientific theory is a hypothesis that has been rigorously tested by the performing different experiments and never been disproven. For example theory of evolution, natural selection which tell us about the evolution of organism on earth which is proven by Darwin. So the right answer is A.

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.