challenge - a situation that needs great mental or physical effort, humanity - people in general, habitable - providing conditions that are good enough to live in, environmental - related to the air, water, and land in or on which people, animals, and plants live, polluted - dirty, ignorance - lack of knowledge, understanding, or information about something, launch - to begin something new, passage - the official approval of something, especially a new law, adopt - to accept or begin to use something,

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