GMAT Critical Reasoning (CR) | Re: The ozone layer that protects life on Earth

The ozone layer that protects life on Earth from harmful UV rays is showing promising signs of recovery, according to a report issued by the UN Environment Program and the World Meteorological Organization. Although levels of ozone depletion remain high, the rate of depletion has not increased for over a decade and in some places there are signs of the layer thickening.

Which of the following, if true, most strengthens the above argument?

A. CFCs and similar compounds deplete ozone because when