Read the given passage and answer the following questions:

'Bad’ ozone, formed in the lower atmosphere (troposphere) that harms plants and animals. There is ‘good’ ozone also; this ozone is found in the upper part of the atmosphere called the stratosphere, and it acts as a shield absorbing ultraviolet radiation from the sun. UV rays are highly injurious to living organisms since DNA and proteins of living organisms preferentially absorb UV rays, and its high energy breaks the chemical bonds within these molecules. The thickness of the ozone in a column of air from the ground to the top of the atmosphere is measured in terms of Dobson units (DU). Ozone gas is continuously formed by the action of UV rays on molecular oxygen, and also degraded into molecular oxygen in the stratosphere. There should be a balance between production and degradation of ozone in the stratosphere. Of late, the balance has been disrupted due to enhancement of ozone degradation by chlorofluorocarbons (CFCs). CFCs find wide use as refrigerants. CFCs discharged in the lower part of atmosphere move upward and reach stratosphere. In stratosphere, UV rays act on them releasing Cl atoms. Cl degrades ozone releasing molecular oxygen, with these atoms acting merely as catalysts; Cl atoms are not consumed in the reaction. Hence, whatever CFCs are added to the stratosphere, they have permanent and continuing effects on Ozone evels. Although ozone depletion is occurring widely in the stratosphere, the depletion is particularly marked over the Antarctic region. This has resulted in formation of a large area of thinned ozone layer, commonly called as the ozone hole.UV radiation of wavelengths shorter than UV-B, are almost completely absorbed by Earth’s atmosphere, given that the ozone layer is intact. But, UV-B damages DNA and mutation may occur. It causes aging of skin, damage to skin cells and various types of skin cancers. In human eye, cornea absorbs UV-B radiation, and a high dose of UV-B causes inflammation of cornea, called snow-blindness, cataract, etc. Such exposure may permanently damage the cornea.

What do you understand by Ozone hole ?

Reduction in thickness of ozone layer in the stratosphere.

The correct answer is Option (2) – Reduction in thickness of ozone layer in stratosphere .

The "ozone hole" is a region of significantly reduced ozone concentration in the stratosphere. The ozone hole occurs in the stratosphere, which is the part of the atmosphere that contains the ozone layer responsible for filtering out harmful UV radiation. It is characterized by a reduction in the density of ozone molecules, leading to a thinner protective layer, rather than a complete absence of ozone. The main cause of the ozone hole is the release of CFCs and other pollutants that rise to the stratosphere and release chlorine atoms upon exposure to UV light. These atoms catalytically destroy ozone molecules. The thinning of the ozone layer allows more Ultraviolet radiation to reach the Earth's surface, which can cause increased rates of skin cancer, cataracts, and other health and environmental issues.