The correct option is A.
The serosa refers to the outermost layer of loose connective tissues which is often covered by mucus and which contains blood vessels. In the gastrol intestinal tract, the serosa refers to the outermost layer of the wall of the GI tract. One major function of serosa is to reduce friction from muscle movement.
The person who studies living things is called a biologist
Answer:
Beavers and their dams play an important role in nature. Because of the dramatic effects their dams have on surrounding ecosystems, these mammals are considered a keystone species. By constructing dams they create wetlands -- lush environments which attract fish, ducks, frogs and other creatures.
Explanation:
