If a keystone species is removed the whole ecosystem will collapse because it relies on that one species.
Excuse me... The question isn't clear I think there are some options or something, it would be helpful for us to answer if you add those too.
Answer:
Fault
Actually, faults are fractures in Earth's crust where rocks on either side of the crack have slid past each other. Sometimes the cracks are tiny, as thin as hair, with barely noticeable movement between the rock layers
Explanation:
The correct answer is: mucosa
The alimentary canal or gastrointestinal tract consist of four layers: mucosa, submucosa, muscular layer and serosa.
Mucosa is the layer that surrounds the lumen, so it is exposed to the food . Mucosa is composed of epithelium (active in absorptive and secretory processes), lamina propria (connective tissue) and muscularis mucosa (peristaltic movement).
