The black rhinoceros (Diceros bicornis) is a massive, double-horned species that has grayish rather than black skin coloring. These independent animals typically live in damp forest, desert, shrubland, savanna and grassland habitat of Africa, from South African and Tanzania to Zimbabwe and beyond. As of 2012, black rhinos have been assigned "critically endangered" population status by the IUCN Red List of Threatened Species. Critical Endangered The "critically endangered" classification of the black rhino is due to the species' immense, 97.6 percent population drop from the beginning of the 1960s. At around the closing of 2010, the estimate for the population of black rhinos was 4,880 specimens. Due to conservation efforts, including designated havens for the species, however, numbers of black rhinoceroses are seeing consistent improvement. In 1995, fewer than 2,500 black rhinos roamed the wild. Poaching Unlawful poaching activities are a severe risk for black rhinoceroses. Since the 1970s, poaching has been a major culprit behind the reduced population of these herbivores - all in pursuit of their horns, which are used for the production of both daggers and medicine. Poaching may be the biggest concern for black rhinos' continued existence as a species, according to the World Wildlife Fund. Black rhinos are very susceptible to poaching for a variety of reasons, one of which is their bad vision, according to the San Diego Zoo Library. If a black rhino cannot see a poacher approaching, it makes it a lot harder to escape. Other Causes of Black Rhino Endangerment Even though poaching certainly takes the front seat in the critical endangerment of black rhinoceroses, habitat alterations also contribute to lowered numbers of the species. Black rhinos are also sometimes perceived by the public as being menacing and unstable animals to human beings, and as a result of that, are also frequently killed. Missions to Save Black Rhinos Apart from the establishment of protected havens for black rhinos to roam about freely and safely, illicit trading for their horns has been forbidden on an international scale. Captive breeding programs around the world are also in full swing, including one at the Taronga Western Plains Zoo of New South Wales, Australia. 31: The word "habitat" in paragraph 1 can be best replaced by _________. A. reserve B. natural environment C. generation D. diversity 32: The serious cause of the black rhino endangerment is _________. A. habitat alteration B. their bad vision C. trading for their horns D. poaching 33: The pronoun "which" in paragraph 3 refers to _________. A. rhinoceroses B. species C. horns D. herbivores 34: According to the last paragraph, which of the following is NOT TRUE about measures to protect black rhinos? A. Illegal trading for their horns has been banned. B. Their horns aren’t used to produce medicine. C. People build reserves so that they can walk freely and live securely. D. Captive breeding programs around the world are successful. 35: What is the main idea of this reading passage? A. There are some causes of black rhino endangerment and efforts to save them from extinction. B. International trading for black rhinos’ horns has been prohibited. C. A black rhino find it not easy to escape if it can’t see a poacher approaching. D. In 2021 black rhinos are considered as critically endangered species.