Bladder, I believe. But they are saying that my answer must be 20 Characters long...
Answer:
I'd say it's A,
Explanation:
It covers all answers listed, and well its just true lol.
Nonpolar and small polar molecules<span> can pass </span>through the cell membrane<span>, so they diffuse </span>across<span> it in response to concentration gradients. Carbon dioxide and oxygen are two </span>molecules<span> that undergo this simple diffusion </span>through<span> the </span>membrane<span>. The simple diffusion of water is known as osmosis.</span>
The Peritoneum is a lining on the inside of the abdomen and on the outside of organs like the intestines and liver. <span> It's sort of like a thin internal skin.
so i think the answer your looking for is Peritoneum.</span>
