Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks.
Since the world has become industrialized, there has been an increase in the number of animal species that have become extinct or nearly extinct. Bengal tigers, ___(1)___ were once found in a large number in jungles, now are thought to be only 2,300 in number. By the year 2025 their ___(2)___ in the world is estimated to be down to zero. The dangerous thing is that people don't hunt them for money but mainly ___(3)___ they enjoy hunting them. Animals like the Bengal tiger, as well as other endangered species are very important to the world's ecosystem. International laws protecting these animals must be passed to save them. Countries around the world have begun to solve the problem in many ways. Reserves and national parks have been established. Money provided by world organizations has been spent on maintaining the parks. The use of products made from ___(4)___ species has been stopped.