Animals that uses simple diffusion respiration

Flatworms and cnidarians

Explanation:

In simple organisms, such as cnidarians and flatworms, every cell in the body is close to the external environment. Their cells are kept moist so that gases diffuse quickly via direct diffusion. Flatworms are small, literally flat worms, which 'breathe' through diffusion across the outer membrane

the answer is g1

it's anything that aren't producers and consumers.

explanation:

you've got to be clear on what "this" is