Density is measured in mass per volume thus C would be the answer.
2.17 g / cm³
<em>A placental mammal develops before its body systems can function independently;</em>
A. Inside it's mothers body
<u>Mammals don't come from eggs, and the term placental mammal means it has a placenta. It comes out when our mothers deliver. A marsupial mammal forms in a pouch, so the answer is inside it's mothers body </u>