On March 14 this year, it was the eighth world kidney day. This time, world kidney day put forward the slogan "Donate kidney to prolong life". Kidney is the most important thing excreted by human body. The formation of urine is filtered by glomerulus and reabsorbed by renal tubules. When the original urine flows through the renal tubule, most of the water, some inorganic salts and all glucose are reabsorbed into the blood, while the rest, such as urea, some inorganic salts and water, flow out of the renal tubule to form urine. Therefore, the formation of urine includes two processes: filtration and reabsorption, in which reabsorption occurs in renal tubules.

So choose: C.