Europa is one of Jupiter's moons. Its surface is covered with frozen water. It is far from the sun and has only a very thin atmosphere, so its surface is considered to be too cold to support life. Beneath the ice, there are probably liquid oceans rich in oxygen, kept warm by heat that escapes from Europa's core. Image courtesy of the NASA/Goddard Space Flight Center Scientific Visualization Studio

Which of the following facts supports the idea that life could exist on Europa?
A.
On Earth, most producers get their energy from sunlight and form the base of entire food webs.
B.
On Earth, deep sea fish attract prey with light that is given off by their bodies.
C.
On Earth, penguins live and breed in the coldest part of the Earth—Antarctica, on the southern polar ice cap.
D.
On Earth, whole ecosystems exist deep in the ocean that use volcanic vents, not sunlight, as a source of energy.