Io Has the Most Volcanic Activity in the Solar System

Multiple Choice

Io has the most volcanic activity in the Solar System because

A) it is continually being bombarded with material in Saturn's E ring.
B) it is one of the largest moons and its interior is heated by radioactive decays.
C) of gravitational friction caused by the moon Enceladus.
D) its interior is tidally heated as it orbits around Jupiter.
E) the ice on the surface creates large pressure on the water below.