Which of the Following Is the Most Convincing Observation That

Which of the following is the most convincing observation that suggests that like Europa, Ganymede may also have a subsurface ocean?

A) the detection of salts on the surface that may have been brought up from below the crust
B) the presence of young grooved terrain that may be the result of cryovolcanism
C) the fact that it is the largest moon in the solar system and, hence, should have plenty of internal heat to maintain liquid water beneath its surface
D) in addition to its internal magnetic field, Ganymede has a magnetic field induced by Jupiter which is consistent with a salty ocean beneath its crust