Final answer:
The discoveries made by New Horizons at Pluto show surprising geological activity, including mountains of water ice, but do not directly match any of the given multiple-choice options.
Step-by-step explanation:
The New Horizons spacecraft made some remarkable discoveries during its recent flyby of Pluto. Geological activity was one of the surprising finds, evidenced by the contrasting areas of Pluto's surface such as dark cratered terrain, light-colored basins of nitrogen ice, and especially mountains of frozen water ice that are possibly floating on nitrogen ice, suggesting recent geological changes. However, while there is mention of geysers on Neptune's moon Triton, caused by the evaporation of Triton's polar cap, the question's options seem to mix up these observations. Therefore, based on the information provided, none of the given options a), b), c), or d) accurately describe the discoveries made by New Horizons at Pluto. Instead, the discoveries point to surprising geological features and active geology on a dwarf planet thought to be cold and inactive.