A tropical   rain forest is an amazing place. Thousands of different kinds of plants and animals make their homes there. Some are not found anywhere else in the world. If the rain forests are not protected, some species of plants and animals could disappear forever, taking their resources   with them. Scientists have known for a long time that medical cures can come from plants. The rain forest is the perfect habitat for various types of plants. They compete for space, sunlight, water, and nutrients. The plants that survive are strong. They also contain many types of chemicals. These chemicals are part of the plants' defence system. They can help protect the plants from bacteria, insects, diseases, and other threats. Experts believe that some of these chemicals might be useful to human beings, too. The native people of the rain forests have healers   who help those who are sick. For hundreds of years, they have known which leaves, roots, and berries can be used to treat different illnesses. Western scientists have begun working with these native healers. They learn about different plants, cures, and treatments. Then, they can perform tests on the plants to see what chemicals they contain and how they might be used. When they do find something important, it goes through more and more tests. Lots of experiments must be done over a long period of time before something can be safely sold as a drug. Scientists want to be sure that it works and that the risk of using it isn't too high. American scientists have set up labs in the countries where the rain forests are. They do studies and research there. They also employ scientists and workers who live in these countries to help them. This allows the local people to benefit from research on the rain forests. They can make money from the rain forest without destroying it, which is very important. If the rain forest is valuable to them, they will help protect it. The more people who are trying to protect the rain forests, the better. Just imagine the cures that might be found there! The text is mainly about_.
the native healers of the rain forests the plants and animals living in the rain forests the medicinal value of plants in the rain forests the diseases which attack plants in the rain forests