On the planet earth, most of the freshwater exists as ice caps and glaciers. Out of the remaining freshwater, the largest proportion
Explanation
The distribution of Earth's freshwater is a standard physical geography fact. The vast majority of freshwater is locked in ice caps, glaciers and permanent snow. Of the remaining unfrozen freshwater, the largest single reservoir is groundwater. Groundwater in aquifers, including shallow and deep systems, constitutes a much larger share than surface freshwater bodies like lakes and rivers, atmospheric moisture, or soil moisture. Thus option c, 'exists as groundwater', is the correct choice in conventional Earth water budget accounting.
To elaborate on magnitudes: glaciers and ice hold about 68-69% of global freshwater. The next largest store is groundwater, which holds roughly 30% of the freshwater after excluding ice, vastly exceeding the volumes in lakes, rivers, and the atmosphere. Freshwater lakes and rivers together constitute a very small percentage of total freshwater, and atmospheric water as moisture and clouds is negligible by volume compared with groundwater. Soil moisture is also a minor reservoir relative to groundwater. These quantitative relations are frequently tested in prelims and must be recalled accurately.
Why other options are wrong: option a, atmosphere, is attractive because we experience weather, but the atmosphere holds only a tiny fraction of freshwater at any time. Option b, lakes and rivers, contains important surface water but their combined volume is far smaller than groundwater. Option d, soil moisture, is critical for ecosystems and agriculture but is limited in total volume and residence time. Groundwater, in contrast, represents a large, relatively stable reservoir distributed in subsurface aquifers and thus dominates the non-ice freshwater stock.
Exam technique note: remember the two largest stores by far are ice and glaciers first, then groundwater. Many students mistakenly emphasize lakes and rivers because they are visible, but in objective tests you must prefer groundwater when asked about the largest share of remaining unfrozen freshwater. Therefore option c is the correct and defensible answer with high confidence.