Refer to Animation: Greenhouse Effect. Which of the answer choices is false? Approximately 50% of the sun's light energy does not reach the surface of the Earth. The Earth radiates heat energy back to the atmosphere. The greenhouse gases in the atmosphere have all come from human activity. Much of the heat that is lost from the Earth's surfaces is re-radiated back into the atmosphere by greenhouse gases. Light energy from the sun warms the surface of the Earth's continents and the ocean.

The gases that are able to absorb and re radiate infra red radiation and heat and due to absorbing heat capacity trap and hold the infrared radiation and its heat known as green house gases. These groun house gases include methane, water vapor, CFC, carbon dioxide, ozone and nitrous oxide.

If the green house gases are not present naturally on earth there wouldn't be enough radiation or heat to prevent earth from freezing. The gaseous are form and use through various cycles.

However, a huge amount of carbon dioxide, CFC and methane are added by the human activity into the atmosphere, which is leading to trap heat more than required and cause green house effect.

Thus, the correct answer would be : The greenhouse gases in the atmosphere have all come from human activity.