Conservation also includes a concern for the quality (1)_______ the environment, so that people can enjoy living in it. It means keeping it (2)_______ and safe - and an (3)_______ place to live in. A healthy environment includes clean streets and highways, with open spaces in cities for parks and playgrounds. Ideal surroundings mean (4)_______ free of junk and litter. They include regions of wilderness where animals and plants can be (5)_______ from the destructive influence of human beings .