Jupiter's Moon Io Is Thought to Be the Volcanically Active

Multiple Choice

Jupiter's moon Io is thought to be the volcanically active world in our solar system. What is the inferred source of heat?

A) Io has a strong magnetic field as does Jupiter, so as Io moves through Jupiter's magnetic field, large electrical currents are generated, which heat the planet.
B) It is a mystery; it should be very cold because it is the same size as the moon but far from the sun.
C) Io is close to Jupiter, and the strong tidal forces on planet produce frictional heating of the planet.
D) Very high abundances of radioactive elements have been detected on the planet.