The right answer is d. all of the above.
The ozone layer is a layer of the Earth's stratosphere that lies between 20 and 50 km above sea level. It is characterized by a concentration of ozone (O3) proportionally greater than in the other layers of the atmosphere, of the order of ten parts per million (ppm).
It has the particularity of absorbing most of the ultraviolet radiation from the Sun that is harmful to life (such as UVB, which can alter the DNA).
The absorption of ultraviolet light by ozone creates a heat source that forms the stratosphere (a region where temperature increases with altitude). It plays a decisive role in the structure of the Earth's atmosphere temperature.
In the troposphere: tropospheric ozone is the one that results from human activities, particularly exhaust gases, which are subject to rigorous monitoring and warning of air quality during periods of intense heat (peak of ozone). This is the "bad" ozone, so it must remain at a low concentration.
