In Biology Lab,you Are Observing and Dissecting Flatworms

Multiple Choice

In biology lab,you are observing and dissecting flatworms.Their bodies are very thin,even see-through,and their thin body surface allows them to exchange gases of oxygen and carbon dioxide with the underlying cells and tissues.Flatworms lack which of the following anatomical systems?

A) excretion
B) nervous
C) movement
D) digestive
E) respiratory