If it is a schematic diagram of the formation process of human urine, the liquids indicated in ① and ② are () A, ① urine, ② blood B, ① original urine and ② blood.

The picture shows the formation process of urine, in which A stands for glomerulus, B 1 stands for renal capsule cavity and C 2 stands for renal tubule.

The formation of urine includes filtration of glomerular and renal capsule wall and reabsorption of renal tubules.

Glomerular filtration: When blood flows through glomerulus A, other substances, such as water, inorganic salts, urea and glucose, will be filtered into renal capsule B, forming protourine; So the liquid represented here is raw urine.

Renal tubular reabsorption: When raw urine flows through renal tubular C, most water, some inorganic salts and all glucose are reabsorbed into blood, and the rest, such as urea, some inorganic salts and water, flow out of renal tubular to form urine. So the liquid shown in ② is urine.

So choose C.