Vasa recta blood osmolality is critical to maintaining the countercurrent mechanisms of the nephron. where is vasa recta blood osmolality the highest?

The vasa recta blood osmolality increases as it descends into the inner medulla. The vasa recta blood serves as the countercurrent exchanger in the mechanism of the nephron in which it is responsible for exchanging the water and the salt between the loops of the vasa recta and the medullary interstitial space.

idk but if i had to take an educated guess i’d say a c d