Which transitions show the correct relationships? Global Warming and Its Causes

Global warming is a result of an increase in greenhouse gases. Greenhouse gases are released into the atmosphere
deforestation and combustion of fossil fuels.
Deforestation is a major contributor to global warming. Forests help to maintain the levels of oxygen in the air that make it possible for us to survive.
, there has been a surge in the levels of carbon dioxide in the air
the depletion of vast stretches of forests.
, other factors, such as the release of CFCs from refrigerators and pollutants from industries into the atmosphere, are also responsible for global warming.