4 October is celebrated as –

World Ocean Day
World UFO Day
World Animal Day
World Population Day

The correct answer is: World Animal Day.

World Animal Day is an international observance celebrated annually on October 4. It was founded in 1931 by Heinrich Zimmermann, a German writer and journalist, and is celebrated by animal welfare organizations around the world. The day is intended to raise awareness of the welfare of animals and to promote kindness and compassion towards them.

World Ocean Day is celebrated on June 8. It is an international observance that aims to raise awareness of the importance of the oceans and the need to protect them. The day was designated by the United Nations in 2008.

World UFO Day is celebrated on July 2. It is an unofficial holiday that celebrates the belief in unidentified flying objects (UFOs). The day was first celebrated in 1994 by UFO researcher Stanton Friedman.

World Population Day is celebrated on July 11. It is an international observance that aims to raise awareness of the world’s population growth and the challenges it poses. The day was designated by the United Nations in 1989.

In conclusion, the correct answer is: World Animal Day.