In terms of osmoregulation, freshwater fish must drink a lot of water and excrete excess salts must have dilute urine and consume salt in their diet have no osmosregulation issues maintain high levels of urea are isoosmotic with their environment

In terms of osmoregulation, freshwater fish must have dilute urine and consume salt in their diet.

Option B

Explanation:

Osmoregulation is a major criteria of that is required for the living of the fishes in the water, the balance of the ionic content between the external water environment of the fish and its internal environment is required for its healthy survival.

the answer will be a) proteins i believe