Answer: I believe the answer is O passing materials in blood to cells
Step-by-step explanation:
The thin walls of the capillaries allow oxygen and nutrients to pass from the blood into tissues and allow waste products to pass from tissues into the blood.
More info: Capillaries
Capillaries - Enable the actual exchange of water and chemicals between the blood and the tissues. They are the smallest and thinnest of the blood vessels in the body and also the most common. Capillaries connect to arterioles on one end and venules on the other.
