The element that is most common in Vitamin D is CARBON.
The nutrients get to the cells in a flatworms solid acoelomate body by diffusion process. Flatworms feed primarily on protozoa and bacteria, smaller worms and tiny organisms, dead or alive, that they come across. Based on the species of the flatworms , they also consume plant materials. They rely on diffusion to transport oxygen and nutrients to their internal tissues.
The answer is D its tightly packed cells allow for proctection against harmful substances.
Earth's service would be bare. There would no longer be life and all water ways would become dried up due to the intense ultra-violent rays of the sun.
