Answer:
Conservation of air.
Explanation:
Conservation of air will result due to greatest decrease in the burning of fossil fuels because fossil fuels greatly damage the air. The burning of fossil fuels produces carbondioxide gas in large amount that can be released in the atmosphere. This increase in carbondioxide gas in the air causes pollution that leads to global warming as well as health problems in humans. So we can conclude that decrease the use of fossil fuel leads to conservation of air.