A. <span>A flatworm doesn't have a coelom
Flatworms and other invertebrates belong to a specific group called </span><span>acoelomate, wherein they lack a coelom and has an internal cavity which serves as their digestive cavity.</span>
The inner planets are those that orbit closer to the sun: mercury, venus, earth and mars.
Attending to the size this is the increasing order: mercury, mars, venus and earth.
Earth is the largest of the inner plantes.
Drinking salt water is harmful because it messes up the salt concentration in each of your red blood cells. It over loads the salt in it and causes the cell to swell up and burst due to it trying to let in more water to balance the salt concentration out.