Assertion: Chlorofluorocarbons are responsible for ozone depletion.
Reason: The ozone level decreases by as much as \[67\% \] every year.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
C. Assertion is correct but Reason is incorrect.
D. Both Assertion and Reason are incorrect.

Hint: Chlorofluorocarbons or CFCs are the chemicals that are widely used in refrigerators and air conditioners. Ozone is the triatomic molecule of oxygen. it is found in the lower and the upper atmosphere. Moreover, the ozone protects us from the harmful ultraviolet rays of the sun.

Complete answer: Let us look at the statements that are given to us one by one.
Assertion: Chlorofluorocarbons are responsible for ozone depletion.
This statement is completely true. Chlorofluorocarbons are discharged mainly from the refrigerators as the refrigerant gases and air conditioners. When these CFCs are released in the lower parts of the atmosphere, they move upwards to reach the stratosphere. In the stratosphere, the CFC molecules decompose to release the chlorine-free atoms but the subsequent action of the ultraviolet rays. These free chlorine atoms react with the ozone molecules and convert them into molecular oxygen. Thus, the CFCs bring out the decomposition of the ozone layer. Therefore, this Assertion statement is correct.
Reason: The ozone level decreases by as much as \[67\% \] every year.
This statement is completely true. Every year the ozone level decreases by as much as \[67\% \]. Due to this more and more ultraviolet rays reach the earth’s surface. These radiations are harmful to humans as they cause eye cataracts, skin cancer, etc. types of diseases in humans. Also, they are harmful to plants and animals. Therefore, the Reason statement is correct. However, this statement does not explain the Assertion at all.
Thus, based on the above information we can conclude that Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion. Hence, the correct answer is option (B).

Note: Ozone depletion is widely occurring in the stratosphere. However, it is seen the most in the Antarctic region each year between late August and early October. An ozone hole can be observed above the Antarctic region. The destruction of the ozone layer was discovered by the scientists Sherwood Rowland, Mario Molina, and Paul Crutzen, for which they were honored with the Nobel Prize in 1995.