The increase of carbon dioxide in the atmosphere creates a greenhouse effect.
To explain this usually some sunlight is reflected back into space while some is absorbed by the earth keeping the planet warm. However the increase in greenhouse gases such as carbon dioxide prevent the light from reflecting back into space and this light becomes trapped causing the earth to heat more then it should. You can almost think of the trapped heat from the greenhouse gases as a blanket around the earth trapping the heat in.
I think the correct answer from the choices listed above is option C. Cells in multicellular organisms differentiate as they continue to divide and increase in size because cells will now perform special functions and have become different to other cells. Hope this answers the question.
The answer would be a Farm house