Answer:
hope this helps you out good luck
I think the answer is "It's tightly packed cells allow for protection against harmful substances."
The mediastinum is the space between the lungs. Organs in it include the heart, esophagus, aorta, and part of the thymus gland.
"<span>The shape of an enzyme determines which reaction it can catalyze" would be the best option from the list, since most enzymes can only do their job if they "fit" into the structure that they wish to enhance, or "speed up". </span>
