What Is the Primary Method by Which Materials Such as O₂

What is the primary method by which materials such as O₂, CO₂, and nutrients are exchanged between the blood and surrounding tissues?

A) passive diffusion of substances across the capillary wall down their concentration gradients
B) active transport of materials across the capillary wall
C) osmotic pressure drawing water and solutes out of the capillary and bringing these dissolved nutrients into contact with the tissue cells
D) processes of ultrafiltration and reabsorption
E) bulk flow