The body fluid of sharks has a much lower concentration of sodium chloride than that of the surrounding seawater, and yet they are able to remain in osmotic equilibrium with the external environment. How can this be the case? A. Sharks store enough urea in their bloodstream to match the total solute concentration of the surrounding seawater. B. Sharks are osmoregulators. C. Sharks maintain high levels of sodium chloride in their skin. D. Sharks drink large volumes of seawater to compensate for the low salt concentration of their body fluids. E. None of the answer options is correct.