Final answer:
Freshwater tends to flow towards rivers, lakes, or become groundwater. Freshwater ecosystems, which occupy only 1.8 percent of the Earth's surface, provide critical ecosystem services and support a diversity of life forms. Therefore, the most appropriate correct option is B.
Step-by-step explanation:
Freshwater in a biological system tends to flow towards different destinations depending on the terrain and the water cycle. The primary options include rivers, lakes, and groundwater. Specifically, rivers are bodies of flowing water that begin at headwaters and travel towards larger bodies of water, such as lakes or the ocean. Rivers and streams are capable of dissolving oxygen and nutrients, making them vital ecosystems for various species. Conversely, lakes are larger bodies of standing water in terrestrial landscapes that are interconnected with the surrounding biotic and abiotic factors. Groundwater is another destination for freshwater, seeping into aquifers that may later surface as springs or contribute to rivers and lakes.
Freshwater ecosystems are characterized by their low salt concentration and support a diverse range of plants and animals, such as fish, amphibians, and insects. These ecosystems provide critical ecosystem services to humans, such as drinking water, crop irrigation, sanitation, and industry. However, such freshwater systems are the rarest, covering only 1.8 percent of the Earth's surface.