The correct answer is - D. all of the above.
The rainforests in the world are in big danger because of the human activities, and the areas they are occupying are constantly becoming smaller and smaller.
The humans see an opportunity for profit form the rainforests in the way of harvesting high quality lumber and than sell it. Also, a huge problem has been the growing population, because more and more food is needed, in order to satisfy the demand, more agricultural land is needed, and very often, the rainforests are the ones that suffer by being cleared up and the are to be used for farming afterwards. Even though it may not seem as something as serious, the building of the roads through the rainforests is a very big problem, not just that for its construction tens of thousands of acres are cleared, but also because lots of animals are being killed on the roads, as they do not know how dangerous they are, or how to behave on them.