Triploblasts may develop an internal body cavity derived fro…

Triploblasts may develop an internal body cavity derived from mesoderm, called a coelom. This epithelial-lined cavity is a space, usually filled with fluid, which lies between the digestive system and the body wall. It houses organs such as the kidneys and spleen, and contains the circulatory system. Which of the following statements about the germ layers is TRUE?