I don’t know the answer to that sorry.
Theory is the correct answer. A scientific theory explains something about the natural world and can be tested via the scientific method to provide a reliable account of why something happens. If it has been suitably tested, it can be provisionally accepted by the scientific community.
What is it for tho. ?
The continents that currently have sufficient water to meet the needs of their populations are North America, South America, Africa, and Australia.
The remaining continents do not - and they have to find their water elsewhere in order to provide all people with enough water for their everyday needs.