Which of the Following Statements Best Explains How Planarians Can

Multiple Choice

Which of the following statements best explains how planarians can survive and thrive without respiratory or circulatory systems?

A) none of their cells are far removed from the gastrovascular cavity or from the external environment
B) they lack mesoderm as embryos and, therefore, lack the adult tissues derived from mesoderm
C) their flame bulbs can carry out respiratory and circulatory functions
D) their body cavity, a pseudocoelom, carries out these functions