I think the correct answer from the choices listed above is option A. It is the alveoli that is composed of single layer <span>surrounded by a network of capillaries. These are used to allow oxygen and carbon dioxide to move from the lungs to the bloodstream.</span>
Because the organism is distributed across the world, and isn't seen anymore, scientists can conclude tat they must have evolved. They can compare one species to the fossils they may have found, and determine that they were related. Then by looking at the species on another part of the world compare the same fossils to other animals and determine that they are similar, sharing a common ancestor.
Answer:
Homologous structures are structures that are similar in related organisms because they were inherited from a common ancestor. These structures may or may not have the same function in the descendants. Figure below shows the hands of several different mammals. They all have the same basic pattern of bones
