Final answer:
The most-used renewable energy source worldwide is hydropower, followed by traditional biomass; though wind and solar are growing, they made up less than 1% of total global energy in 2008. (option c)
Step-by-step explanation:
The most-used renewable energy source worldwide is hydropower (option c). While wind energy and solar energy have been gaining ground rapidly, they are still a smaller fraction of the world's total energy needs compared to hydropower. Hydropower uses the flow of water to generate electricity and has been an established form of energy production since the 20th century. It is seconded by traditional biomasses, such as fuel wood, used in traditional societies for household needs. However, these traditional biomasses are not always employed sustainably. Wind and solar electricity, although growing, contributed less than 1% of total energy in 2008. With increasing attention to renewable energy sources, the consumption of these resources is expected to rise from 15% in 2018 to 28%, with a shift towards non-fossil fuels driven by concerns over climate change and carbon dioxide emissions.