When blood flows through the glomerulus, uric acid, urea, water, inorganic salts and glucose in the blood enter the renal capsule through the filtration of the glomerulus, forming protourine; When the original urine flows through the renal tubule, all glucose, most water and some inorganic salts are reabsorbed by the renal tubule, and these reabsorbed substances enter the capillaries around the renal tubule and are sent back to the blood, and the rest of the water, inorganic salts and urea form urine. Therefore, a person can form 1.5L of raw urine a day, but only about 1.5L of urine can be excreted, mainly due to the heavy renal tubules.
So choose: C.