The correct option is B Burning of waste
One way of dealing with waste is to burn it down. It does reduce the volume of waste, but the burning of waste releases a lot of greenhouse gases in the atmosphere, thus causing air pollution. Sometimes even if burning is not done intentionally, some accident might cause it. For example, one such incident occurred in Deonar dumping ground in Mumbai in 2016, that had led to a large portion of the city being covered in toxic plumes. That is why, to minimise the air pollution, waste should be burned inside a properly designed furnace under very carefully controlled conditions.