Some Large, Multicellular, Aquatic Animals Have No Circulatory System

Multiple Choice

Some large, multicellular, aquatic animals have no circulatory system. They manage gas exchange

A) by bringing the external environment (with its supply of oxygen) inside their body.
B) by means of endosymbiotic bacteria that produce oxygen inside their tissues.
C) solely by diffusion from outside their bodies.
D) by basking at the surface periodically to allow for diffusion of oxygen.
E) None of the above