The substance is a compound because it's formed by two different elements.
Ok mauguguv is there a lot more and more than a few minutes later I can have
Among the non-mammalian vertebrates, the cloaca is an anatomical structure that function as a shared pathway for the digestive, excretory, and reproductive systems. Cloaca in vertebrates, common chamber and outlet into which the intestinal, urinary, and genital tracts open. It is present in amphibians, reptiles, birds, elasmobranch fishes, and monotremes. Cloaca is not present in placental mammals or in most bony fish.
Protoplanets are bodies or celestial objects which have the same size as the moon or a bit bigger. These bodies develop to eventually become planets. Therefore, the answer to this item is most likely letter D. outer planets.