The correct answer is - A) global population expansion.
The graph shows us the area that is covered with forest, the Amazon rain forest, and has it has been declining over the years. The deforestation is a direct result of the growing population of the people on the planet. Because there are more and more people, more and more land is needed for production of food, more timber is required for producing different things for the every day lives of the people, and more and more space is needed for building homes. All of this directly affects the forest, it is the one that has to be cleared and taken down in order to enable the things that people need and like to be made.