16. Most aquatic animals excrete ammonia, while land animals excrete urea or uric acid. What is the most likely explanation for the difference?
A. land animals cannot afford the energy needed to make ammonia
B. they have different diets.
C. ammonia is very toxic and it takes lots of water to dilute it.
D. fish need to get rid of ammonia, but land animals need it to live
E. land animals can get the extra energy needed to make urea or uric acid.

It would be C

Explanation:

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.