Answer:
conserve; copious; dilute. (Ans. C).
Step-by-step explanation:
Osmosis is defined as where a weak solution will always try to gain a strong solution, and dilute it until the balanced concentration is reached. Freshwater fishes surrounding environment is contain weak solutions compare to their internal fluids, so the water is trying to invade the fish body internal fluids.
Fishes have kidneys which helped them to process large amount of fluid, and are able to pass diluted urine from the body. Because fishes urine is diluted in nature they are able to conserve salt while lots of fluids passing away from body.