Which Choice Describes the Countercurrent Mechanism of the Nephron Loop

Multiple Choice

Which choice describes the countercurrent mechanism of the nephron loop?

A) Water moves out of the ascending limb; sodium moves into the ascending limb
B) Water moves into the ascending limb; sodium moves out of the ascending limb
C) Water moves out of the descending limb; sodium moves out of the ascending limb
D) Water moves into the descending limb; sodium moves out of the descending limb