VIII. Read the passage carefully, then choose the correct answer.

Since the world has become industrialized, there has been an increase in the number of animal species that have either become extinct or have neared extinction. Bengal tigers, for instance, which once roamed the jungles in vast numbers, now number only about 2,300, and by the year 2025 their population is estimated to be down to zero. What is alarming about the case of the Bengal tiger is that this extinction will have been caused almost entirely by poachers who, according to some sources, are not interested in material gain but in personal gratification. This is an example of the callousness that is part of what is causing the problem of extinction.

Animals like the Bengal tiger, as well as other endangered species, are a valuable part of the world‘s ecosystem. International laws protecting these animals must be enacted to ensure their survival, and the survival of our planet.

Countries around the world have begun to deal with the problem in various ways. Some countries, in order to circumvent the problem, have allocated large amounts of land to animal reserves. They then charge admission to help defray the costs of maintaining the parks, and they often must also depend on world organizations for support. With the money they get, they can invest in equipment and patrols to protect the animals. Another solution that is an attempt to stem the tide of animal extinction is an international boycott of products made from endangered species. This seems fairly effective, but it will not, by itself, prevent animals from being hunted and killed.

What does the word “ this refer to in line 8?