Which of the following is both a greenhouse gas and an ozone-depleting substance ?

CFC_s

Ozone gas is continuously formed by the action of UV rays on molecular oxygen, and also degraded into molecular oxygen in the stratosphere. There should be a balance between production and degradation of ozone in the stratosphere. Of late, the balance has been disrupted due to enhancement of ozone degradation by chlorofluorocarbons (CFCs). CFCs find wide use as refrigerants.

Ozone depleting substances (ODS) such as CFCs and HCFCs are also greenhouse gases  .