In the Renal Tubules, Where Is the Na⁺/K⁺ pump Located

In the renal tubules, where is the Na⁺/K⁺ pump located?

A) in the apical membrane of the descending limb of the loop of Henle
B) in the basolateral membrane of the proximal tubules
C) in both the apical and basolateral membranes of principal cells
D) in the apical membrane of the collecting ducts
E) in both the apical and basolateral membranes of intercalated cells