Which of following is something almost everyone can do to reduce his or her carbon footprint? a. heat the house more in the winter b. turn up the water heater c. use a fan instead of air conditioning d. drive the car more often

The correct answer is option C, that is, use a fan instead of air conditioning.  

The greenhouse gases like methane, carbon dioxide, and ozone contribute to ozone depletion, pollution, and global warming. The carbon footprint of humans signifies towards the net amount of greenhouse gases generated by them or by the things used by them, of the things fossil fuels being a prime contributor.  

The things like heating, driving a car, and cooling, and using electrical power from coal and gas discharge carbon dioxide, and enhances the concentration of greenhouse gases in the atmosphere.  

In order to reduce carbon footprint, one can use a fan in place of the air conditioner, as ACs emits chlorofluorocarbons, which can further aggravate the situation of greenhouse gases and can donate more to ozone layer depletion.