Final answer:
The correct option for Io is that it is the most volcanically active body in the solar system, due to tidal heating from Jupiter's gravity.
Step-by-step explanation:
Among the given options, the one that applies to Io is:
A) the most volcanically active body in the solar system
Io, the innermost of the Galilean moons of Jupiter, is intensely volcanic, exceeding any level of volcanism seen on Earth. In fact, it's the highest level of volcanism in the solar system. This volatile activity is due to intense tidal heating as a result of Jupiter's strong gravitational pull.
Contrary to it having a thick atmosphere, Io does not have a significant atmosphere at all, and it's not a Kuiper Belt object captured by Jupiter's gravity. Instead, the moon Europa, another of Jupiter's moons, is the one thought to have a subsurface ocean of liquid water, as a result of the same tidal heating phenomena that make Io so volcanically active.