Final answer:
The rivers in the Amazon Basin are primarily fed by moisture from atmospheric condensation, which is part of the water cycle driven by the sun's energy. The moisture comes from evaporation of oceanic and terrestrial water bodies, which then condenses and precipitates as rain or snow over the basin.
Step-by-step explanation:
The source of the moisture that feeds the rivers in the Amazon Basin primarily comes from atmospheric condensation. The water cycle is driven by the sun's energy, which warms the oceans and other surface waters leading to evaporation and sublimation. This process deposits large amounts of water vapor into the atmosphere. Over time, this vapor condenses into clouds, and eventually, precipitation in the form of rain or snow returns water to the Earth's surface, contributing to the river systems such as those in the Amazon Basin.
While underground springs, glacial meltwater, and other sources can contribute to a river's volume, in the case of the Amazon Basin, the vast majority of the water originates from atmospheric condensation resulting from the evaporation of oceanic and terrestrial water bodies. Additionally, the majority of freshwater on Earth, whether accessible to humans or not, is contained in glaciers and ice caps, followed by groundwater repositories.