Carbon dioxide (CO2) makes up the vast majority of greenhouse gasemissions from the sector, but smaller amounts of methane (CH4) and nitrous oxide (N2O) are also emitted. These gases are released during the combustion of fossil fuels, such as coal, oil, and natural gas, to produce electricity.
I don't know whether this was one of your options, but South Asia can be very well characterized as a Sub-continent.
In fact, it's is commonly referred to as "the Indian Subcontinent" or even simply "Subcontinent". One of the reason for a distinction of this part of the land is that it lies on a different tectonic plate.
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The answer is 2. The fact that mechanized agriculture has replaced manual labor. Hope this helps :)
