Multicellular organisms must keep their cells awash in an "internal pond" because
A) their membranes will crystallize if not in contact with interstitial fluid.
B) an aqueous medium is needed for the cellular exchange of nutrients, gases, and wastes.
C) this prevents the loss of water due to osmosis.
D) their cells need to be protected from dissolved nitrogen gas in the blood.
E) terrestrial organisms have not adapted to life in dry environments.
Answer: B