In order for sharks to maintain a concentration balance with it’s environment, a shark must: A. excrete large amounts of urine B. retain its urine in it’s blood stream
C. retain salt from it’s gills D. transport salt to it’s surroundings

B. retain its urine in it’s blood stream

Explanation:

Sharks are cartilaginous fishes that lives in the ocean. Oceans are always salty, hence organisms need to maintain a salt-water balance between their internal and external environment because of osmosis. Sharks are able to maintain this by ensuring that the amount of solutes in their internal environment is as much as that in their external environment.

Sharks retain a chemical contained in urine called UREA in their bloodstream to counter the osmotic effect of the salt concentration in the waters they live. This helps them maintain a concentration balance with their environment.

cell regulation is conducted by special proteins.