In which part of atmosphere ozone layer is present

Explanation:

The ozone layer or ozone shield refers to a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet (UV) radiation.
It contains high concentrations of ozone (O3) relative to other parts of the atmosphere, although still very small relative to other gases in the stratosphere.

Final Answer:

Ozone layer is present in Stratosphere. Correct option is A.