Which of the following environment events is observed by switching off all lights at homes, business establishments, landmarks, and so on for an hour?

The correct answer is Earth Hour.

Let us understand each option and why Earth Hour is the correct answer to this question.

What is Earth Hour?
Earth Hour is a global environmental awareness event organized by the World Wide Fund for Nature (WWF). It is observed every year on the last Saturday of March, typically between 8:30 PM and 9:30 PM local time.

What happens during Earth Hour?
During Earth Hour, individuals, households, businesses, and even iconic landmarks (such as the Eiffel Tower, Sydney Opera House, and many others) are encouraged to switch off all non-essential lights for one hour. This symbolic act raises awareness about climate change and the importance of conserving energy and protecting our planet.

Why is it called "Earth Hour"?
The event lasts for exactly one hour — hence the name "Earth Hour." It began in Sydney, Australia in 2007 and has since grown into the world's largest grassroots movement for the environment, observed in over 190 countries and territories.

Why are the other options incorrect?

• World Environment Day — Observed on June 5 every year, it is led by the United Nations Environment Programme (UNEP). It focuses on raising awareness and promoting action for the protection of the environment, but does not specifically involve switching off lights.

• Earth Charter — This is not an annual event. The Earth Charter is an international declaration of fundamental ethical principles for building a just, sustainable, and peaceful global society. It was launched in 2000.

• Earth Day — Observed on April 22 every year, Earth Day is a global event to demonstrate support for environmental protection. It may involve various activities like tree planting, clean-up drives, etc., but it does not specifically involve switching off lights for an hour.

Conclusion:
The unique act of switching off all lights at homes, business establishments, and landmarks for one hour is the defining characteristic of Earth Hour. This makes it easily distinguishable from all other environmental events listed in the options.