Which result is the strongest evidence that drug X blocks fluid reabsorption by the thick ascending limb by blocking paracellular Na+ transport?a. This region of the nephron absorbs fluid normally but does not if drug X is present. If Na+ is replaced by choline in the perfusate then the nephron does not absorb fluid and drug X has no effect. Removal of other ions has no effect. b. This region of the nephron absorbs fluid normally but does not if drug X is present. If Na+ is replaced by choline in the perfusate then the nephron does not absorb fluid and drug X has no effect. Removal of K+ or Cl- also blocks fluid reabsorption and the effects of drug X. c. The thick ascending limb absorbs fluid normally but does not when drug X is present. Removal of oxygen has no effect on fluid reabsorption. d. Ouabain blocks fluid transport by the thick ascending limb.