Which of the following statements are correct?
1. Flue gas is emitted as a byproduct of combustion of fossil fuels.
2. SO2 is one of the major greenhouse gases that cause global warming and can cause respiratory problems in humans.
3. Installing Flue Gas Desulphurisation units is a costly affair. According to the Central Electricity Authority, it costs approximately ₹1.2 crore per MW to install.