The Following Graph Depicts the Changes in Tubular Fluid Concentrations

The following graph depicts the changes in tubular fluid concentrations of various substances along the length of the proximal tubule,plotted as the tubular fluid-to-plasma concentration ratio (TF/P).Thus the TF/P = 1 for a substance that is at the same concentration in the tubular fluid and plasma (for all substances that are freely filtered,TF/P = 1 at the glomerulus). Match the following substances to the appropriate TF/P curve. Na⁺