Tidal heating on io causes a. a subsurface water ocean. b. geysers of water at its south pole. c. tectonic surface features. d. sulfur volcanoes

Explanation:

Tidal heating phenomenon occurs due to tidal friction processes, in which the orbital and rotational energy of a body dissipate in the form of heat.

An excellent example of this is one of the moons of Jupiter, Io, which is listed as the body with the highest volcanic activity in the solar system, having volcanoes that expel sulfur and sulfur dioxide in their eruptions, due to the presence of significant amount of sulfurous materials on its surface.

To understand it better:

Jupiter is a huge massive planet, therefore the body that is on the side closest to it will have a gravitational force slightly greater than a body on the opposite side, and it is precisely this difference in gravitational attraction that causes distortions in the form of Io being one of Jupiter's innermost moons.

In addition, this implies that the orbit of Io is very elliptical and eccentric compared to the outer moons, resulting in the distance between Jupiter and this moon being varying considerably over time, as well as the distortion of the shape of Io by the gravitational force.

All this causes the rotation of Io on its own axis to generate intense frictions inside it: tidal heating.