Faced with increasingly severe environmental pollution and ecological imbalances, the slogan "We only have one planet" has a strong shocking power, and it reminds people to pay attention to the importance of environmental protection. Which of the following is closest to the idea of the author of this slogan? ? ['No other planet can have life in the universe.', 'In the universe, even if there is another planet suitable for human habitation, humans cannot move to that planet.', 'It is impossible for humans to find a planet more suitable for themselves than the earth.', 'Only the earth has warm sunshine and plenty of rain.']