Final answer:
Of the options given, 'Swamps and moisture' would be the largest freshwater resource by size in percentage. However, it is essential to understand that the majority of the Earth's freshwater is in ice caps, glaciers, and ground water, not in swamps, moisture, atmospheric water, rivers, or soil moisture.
Step-by-step explanation:
The largest by size of the following freshwater resources, in terms of percentage, are:
- Atmospheric water
- Rivers
- Swamps and moisture
- Soil moisture
Based on the given reference information, Icecaps and Glaciers hold 68.7% of the Earth's freshwater, while Ground Water accounts for 30.1%. Surface Water constitutes only 0.3%, with 87% of that being in lakes and 11% in swamps, leaving rivers with just 2%. As none of the options provided (atmospheric water, rivers, swamps and moisture, soil moisture) directly correspond to the categories listed in the reference, and considering the options available in the question, 'swamps and moisture' would be closest to 'swamps' listed in the reference, therefore 'Swamps and moisture' would be the largest of the given options.
However, it's important to note that glaciers, ice caps, and ground water are by far the largest reservoirs of freshwater. Also, the main water source for land plants is soil (option b), which gains water through surface runoff from precipitation and melting ice.
Lastly, the water distribution on Earth is such that while freshwater is only a very small percentage of the total water volume, with a significant portion locked in glaciers and ice caps, this makes access to drinking water a critical issue, complicating water supply to communities around the world, both for consumption and agriculture, which consumes about 70% of freshwater.