Answer: Diffusion
Step-by-step explanation:
Diffusion can be defined as the movement of particles or substance which travels from a region of their higher concentration to an area where it has a low concentration.
It does not requires energy it is a passive process. It is used by smaller particles or gaseous particles.
It cannot be used for larger and heavier molecules like carbohydrates, fats and proteins as they are large and require energy for its transport.