What portion of the world's freshwater is held by the Great Lakes?

The Great Lakes, which are made up of Lake Superior, Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario, contain approximately 20% of the world's freshwater supply. This significant volume is crucial for both ecological balance and human needs in the region surrounding the lakes. Given that 20% can be mathematically represented as 1/5 when comparing it to the whole, this makes 1/5 the correct portion of the world's freshwater that is held by the Great Lakes.

In contrast, 1/4 (or 25%) and 1/3 (approximately 33.3%) are both larger portions than what is accurate for the Great Lakes' contribution to the global freshwater supply, while 1/10 (or 10%) is too small. The choice of 1/5 accurately reflects the significance of the Great Lakes as a major freshwater resource on Earth.