Cell,tissue,organ,organ stystem,
Answer:
d. the ear drum
Explanation:
In the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear from the middle ear.
I think it's "Respondent Behavior"
The plasma membrane is a special cellular structure that can be found in animals and plants that has the sole role of keeping things together and preventing things from coming in. For these two reasons, it's an important player in homeostasis.