Which human activity will most likely contribute to ozone layer destruction?

CFC gases and methane gases.

Explanation:

Chlorofluorocarbons from the air conditioners are one of the main culprits responsible for ozone layer depletion, that react with the airborne particles in the presence of Sun's radiation breaking the ozone into oxygen atoms and as result creating large ozone hole over the planet. Emission of harmful toxic gases of carbon monoxide and dioxide into the air through the vehicular exhaust also creates an atmosphere full of atmospheric black cloud. Apart from this the various organism taking up O2 release methane a natural gas which can modify and trap this heat content on the earth burning of polybags and tires fossil fuels and coal also release other harmful gases which are considered to be reactive with the atmosphere.