Which of the Following Statements Is NOT True

Which of the following statements is NOT true?

A) Cnidarians circulate fluid in the coelenteron.
B) The differences between an open and a closed circulatory system are clear-cut.
C) Many animals have an internal extracellular fluid that is separate from the environment.
D) The fluid leaving the capillary bed of closed circulatory systems is similar to the hemolymph of open systems.
E) Closed circulatory systems are made necessary by the large size of organisms that have them and the large distances between nutrient sources and cells.