The Primary Disadvantage of an Osmoregulator Strategy Is

The primary disadvantage of an osmoregulator strategy is

A) pumping ions into or out of the body is energetically expensive.
B) pumping ions into or out of the body is not a significant energetic expense usually.
C) keeping relatively constant internal conditions deprives the central nervous system of critical information about the environment.
D) pumping water into or out of the body is energetically expensive.
E) physiological systems do not typically perform well under relatively constant conditions.