The option "2 and 3 only" is correct because Earth Hour is specifically a grassroots movement that encourages individuals, communities, and businesses to turn off non-essential lights for one hour, typically held in March, to symbolize their commitment to combating climate change and promoting sustainable environmental practices. While it effectively raises awareness about climate change and the need for environmental conservation, it is not organized by UNEP (United Nations Environment Programme) and UNESCO (United Nations Educational, Scientific and Cultural Organization); instead, it is led by the World Wildlife Fund (WWF). Thus, statements 2 and 3 accurately convey the purpose and nature of Earth Hour.