On which date Ozone Day is observed?

1. A

   October 2

   (a) claims that Ozone Day falls on October 2, which is celebrated as Gandhi Jayanti in India. This date is associated with national leaders rather than global environmental protocols.

2. B

   September 16

   (b) states that World Ozone Day is observed on September 16. This date marks the anniversary of the signing of the Montreal Protocol on Substances that Deplete the Ozone Layer in 1987, making it the globally recognized day for this observance and thus the correct key.

3. C

   April 29

   (c) suggests April 29, which has no direct global linkage to ozone layer protection campaigns or treaties. Therefore, this option is incorrect.

4. D

   January 30

   (d) mentions January 30, observed as Martyrs' Day in India to mark the assassination of Mahatma Gandhi. It has no connection to environmental ozone agreements.

Summary. Official key is (b) September 16. World Ozone Day commemorates the signing of the Montreal Protocol in 1987 to phase out ozone-depleting substances. Option (a) marks Gandhi Jayanti, while option (d) is Martyrs' Day, confusing national dates with international environmental events. Option (c) lacks any historical tie to ozone treaties. Hence, only option (b) correctly identifies the official observance date.