The correct option is Ozone.
Explanation
Chlorofluorocarbons (CFCs) are synthetic compounds that are chemically stable in the lower atmosphere (troposphere) but become active agents of chemical change when they reach the upper atmosphere (stratosphere).
Detailed Analysis:
- Mechanism of Action: Upon reaching the stratosphere, CFC molecules are exposed to high-energy ultraviolet (UV) radiation. This radiation causes the photodissociation of CFCs, breaking the bond between carbon and chlorine atoms and releasing highly reactive chlorine free radicals (Cl).
- Destruction of Ozone: The released chlorine atom reacts with an Ozone (O3) molecule to form Chlorine Monoxide (ClO) and an Oxygen molecule (O2).
- Catalytic Cycle: The Chlorine Monoxide then reacts with a free oxygen atom to release the chlorine atom back, allowing it to destroy another ozone molecule. A single chlorine atom can destroy thousands of ozone molecules in this catalytic chain reaction.
- Other Options: Carbon Dioxide, Methane, and Nitrous Oxide are greenhouse gases present in the atmosphere. While they participate in various atmospheric reactions, they are not the specific target of destruction by the chlorine radicals released from CFCs in the context of stratospheric depletion.
Key Takeaway:
CFCs release chlorine radicals in the stratosphere under the influence of UV radiation, which catalytically destroy Ozone, converting it into oxygen.