a coelomate animal has a body cavity that is completely lined by what kind of tissue
Coelom The coelom is the main body cavity in most animals[1] and is positioned inside the body to surround and contain the digestive tract and other organs. In developed animals, it is lined with a mesodermal epithelium. In other animals, such as molluscs, it remains undifferentiated.[clarification needed]
Epithelium Epithelium (/ˌɛpɪˈθiːliəm/)[1] is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the outer surfaces of organs and blood vessels throughout the body, as well as the inner surfaces of cavities in many internal organs. An example is the epidermis, the outermost layer of the skin.