Answer: Stratosphere
Explanation:
The ozone layer lies in the stratosphere of the atmosphere. This layer blocks the ultraviolet rays of the sun. The sunlight that reaches from the sun to the earth has harmful ultraviolet rays in it.
The UV-A and UV-B rays can cause mutation and the harmful rays can also affect the skin of the human beings. Exposure to the sunlight can also cause skin cancer.
To protect from these diseases and mutations ozone layer is present in the atmosphere.