Water is not usually thought of as a solid, and only a small fraction of the Earth's water is in a solid state, in the form of ice. This ice includes all forms of frozen water, from the ice sheets at the North and South poles to icebergs, ice on the top of mountains, frozen lakes in the winter, or even the ice in a freezer. Though all the ice on earth is part of the hydrosphere, the frozen aspect is known as the cryosphere. This frozen water is three-fourths of the earth's freshwater, which makes it quite important. Identify other sources of fresh water.

1. rivers, lakes and streams
2. underground water
3. reservoirs and dams
4. All of the above.

All of the above.