The diagram illustrates capillaries and the direction in which materials move. What occurs at points 1 and 2?
- A1: carbon dioxide leaves the blood; 2: urea enters the blood
- B1: oxygen diffuses; 2: red blood cells return to the blood
- C1: tissue fluid leaves the capillaries; 2: waste products enter the blood
- D1: red blood cells move into the tissues; 2: carbon dioxide diffuses