I think the answer you are looking for is that the stomach is the fourth level of organization.
<span>B. Marsupials. </span>Amniotic eggs is a unique kind of egg because they possess a semipermeable shell to protect the egg but it also allows gas exchange. Inside an amniotic egg contains the amnion, chorion and allantois. Animals that lay amniotic eggs are called amniotes, which include reptiles, birds, dinosaurs, monotremes (platypus).
What are you trying to ask?
From top to bottom, I believe the answers are:
Biologist
Chemist
Geologist
Hydrologist
The answer to that will be prokaryotic