What percentage of all the water on Earth is available for human use?

The correct answer reflects a common understanding of the distribution of Earth's water resources. Most of the Earth's water—approximately 97%—is saltwater found in the oceans, which is not suitable for direct human consumption or agricultural use.

Of the remaining 3% of freshwater available, not all is accessible. A significant portion is trapped in ice caps and glaciers, which accounts for about 68.7% of that freshwater. Groundwater makes up about 30% of freshwater, but much of it is too deep or difficult to extract.

The percentage of freshwater that is readily available for human use, which includes surface water from lakes, rivers, and streams, is quite small. In fact, estimates suggest that only about 1% of the total freshwater from the 3% that is freshwater is considered available for direct human use. Thus, when examining the total percentage of water on Earth that is suitable for human consumption and use, the 0.8% figure aligns with these understandings and data. This option accurately captures the reality of water availability in relation to the total water volume on Earth.