Which of the Following Is NOT True About the Vertical

Multiple Choice

Which of the following is NOT true about the vertical osmotic gradient in the kidney?

A) is established and maintained by the countercurrent system.
B) makes it possible to put out urine of variable concentration, depending on the needs of the body, by varying the degree of water permeability of the distal portions of the nephron.
C) is found in the renal cortex.