The correct option is D All of the above
The Na+/K+ ATPase pump is present in the basolateral membrane of the tubular cells. As sodium is maintained in low concentration inside these cells, its concentration will be relatively high in the tubular fluid. This favours diffusion from the tubular filtrate into the tubular cells. The electric gradient and the movement of sodium along with its concentration gradient powers the reabsorption of molecules such as glucose, amino acids, and other ions like bicarbonates, etc. move along with sodium. Basically, the molecules that piggyback with sodium tend to have a high concentration within the cells and therefore once they have entered the cells they automatically diffuse across the cell membrane into the interstitium. From here they are picked up by the bloodstream and finally enter the capillaries.