Explanation:

- Earth Hour (Option 2):

- ?? Correct Answer: Earth Hour is an event organized by the World Wide Fund for Nature (WWF) where participants switch off their lights for one hour to raise awareness about climate change and energy consumption.

- World Environment Day (Option 1):

- Celebrated on June 5 each year, it encourages awareness and action for environmental protection. It does not specifically involve turning off lights.

- Earth Charter (Option 3):

- An ethical framework for building a just, sustainable, and peaceful global society in the 21st century. It does not involve switching off lights.

- Earth Day (Option 4):

- Celebrated on April 22, Earth Day focuses on environmental protection and advocacy. It includes various activities, but not specifically switching off lights.