Earth is composed of four main layers, starting with an inner core at the planet's center, enveloped by the outer core, mantle, and crust. The inner core is a solid sphere made of iron and nickel metals about 759 miles (1,221 kilometers) in radius.
source: nasa
I believe the correct answer to your question is option C. It is a process by which greenhouse gases allow the sun’s light to penetrate the atmosphere but stop the heat from escaping.
The greenhouse effect is the natural heating of the Earth's surface.
Hope I could help! :)
The Tennessee Valley Authority is a corporation that was established as part of FDR's New Deal programs. One of the purposes of this corporation was to avoid the excessive presence of private companies in the modernization of the valley.
The TVA provided people with many jobs during the Great Depression. However, it achieved more than this. The TVA managed the natural environment of the region by controlling flooding and erosion. It also increased industrial activity in the region by building dams and power plants.
