A、The increase of human population. B、The extinction of dinosaurs. C、The cutting down of forests. D、The great demand for animal

You’ve probably heard the slogan "save the whales". Do you know why the slogan began? It’s started as a protest from people who wanted to ban whale-hunting. Some types of whales are among the hundreds of endangered species. Many people believe that it is important to save endangered species to maintain the balance of nature. Already some species are extinct, among them are passenger pigeon, Dodo bird and Labrador duck. of course, dinosaurs are extinct, too, but dinosaurs did not disappear because of humans.
    Today, as the human population increases all over the planet Earth, less and less space remains for other species to live in their natural habitats. Species become endangered for many reasons, and they are all related to humans. For example, we cut down forests and thus destroyed the natural habitats of forest animals. We hunt for fun, enjoyment or excitement, some animals to their extinction or near extinction. We kill to get animal parts, such as bones or furs.
    Since the 19th century, people have been trying to protect wildlife with special programs. The Endangered Species Act was passed in 1973, and by 1998, less than 1,000 animal species were listed as endangered. Such animals as giant pandas and tigers are on the top. These species not only need special measures and extra protection in order to survive, they also serve as "umbrella species". Helping them helps numerous other species that live in the same habitats.
    We must ensure that the planet Earth our children inherit will be home to elephants, tigers, giant pandas, whales and other wildlife species, as well as humans.