A primary reason that the kidneys have one of the highest ...

[j_sun]

A primary reason that the kidneys have one of the highest metabolic rates of all body organs is that
A) it stores the body's excess fats.
B) it has membranes of varying permeability to water.
C) it operates an extensive set of active-transport ion pumps.
D) it is the body's only means of shedding excess nutrients.
E) it has an abundance of myogenic smooth muscle.

[sammy]

I remember it was C

[j_sun]

Thanks dude! Marking this solved.