Concept:The ozone hole means the thinning of the ozone layer found in the stratosphere.
Explanation:The ozone layer is located in the stratosphere, about 15 to 35 kilometres above the Earth.
It absorbs most of the Sun's harmful ultraviolet (UV) radiation.
The term "ozone hole" is not a literal hole in the atmosphere.
It refers to a severe decrease in the thickness of the ozone layer in the stratosphere.
This depletion is mainly caused by chlorofluorocarbons (
CFCs) and other ozone-depleting substances.
The effect is most severe over Antarctica during the southern spring.
Option A is incorrect because there is no actual physical hole.
Options B and D are incorrect because the ozone hole is not defined by changes in the troposphere.
Answer:C. decrease in thickness of ozone layer in stratosphere