A、In the 19th century. B、In 1973. C、In 1998. D、In the 21st century. B

You’ve probably heard the slogan "save the whales". Do you know why the slogan began? It started as protest from people who want 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 hey are all related to humans. For example, we cut down forests and thus destroy 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 products, 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 animals’ species were listed as endangered. Such animals as giant pandas and tiger are on the top. These species not only needs 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 specie as well as humans.
23.Why did people put up the slogan "save the whales"?
24.Which of the following is NOT a cause for the extinction of many a species?
25.When was the Endangered Species Act passed?
26.What is typical of umbrella species?