The correct option is A Both statements I and II are correct
Ozone or O3 is a highly reactive gas composed of three oxygen atoms. It can be formed by natural means and by anthropogenic actions (human activities).
Ozone layer that naturally occurs in the Earth's upper atmosphere (the stratosphere) is called good ozone as it acts as a shield and absorbs UV radiation from the sun. UV rays are highly injurious to living organisms as they cause mutations and a lot of skin related problems such as skin cancers. High dose of UV rays also cause snow-blindness (Inflammation of cornea).
Hence statement II is correct.
The troposphere is the lowest layer of Earth's atmosphere which supports life. Ozone can also be formed in the troposphere by chemical reactions involving naturally occurring gases and gases from pollution sources. It is formed by the interaction of sunlight with hydrocarbons and nitrogen oxides, which are emitted by automobiles and smoke stacks.
Ozone is harmful to plants and animals. When inhaled, ozone reacts with many biological molecules in the respiratory tract, leading to a number of adverse health effects. Hence, in the troposphere, ozone is a pollutant and is called bad ozone.
Hence statement I is correct.