Answer:
Option (B)
Explanation:
When the initially occurring aquatic organisms such as the blue-green algae started to use the solar energy in order to convert the water molecules and carbon dioxide and converting them into organic compounds as well as the molecular oxygen (O₂). This is known as the photosynthesis process that produced a significant amount of oxygen in the atmosphere. These oxygen molecules, as absorbs the UV radiations emitted from the sun, it breaks the oxygen molecules and forms a single atom of oxygen. These atoms then again is added to the molecular oxygen and forms the ozone (O₃) molecule.
This is how the ozone layer has formed about 2 billion years ago.
Thus, the ozone layer did not form during the Cenozoic era.
Hence, the correct answer is option (B).
