In argumentative writing, an author establishes their position on a topic through their

The author usually sets up their thesis statement by explaining the context and reviewing the topic in a general way. Next, as in all writing, the author has to explain why the topic is important. In other words, why should the reader care? Then comes the author's thesis statement.

even though you have attached neither the chart nor the generalizations, i have located them online. the right answer is d, since they are asking you about a generalization. you can only infer from the chart that between 2008 and 2009 the number of employed workers decreased significantly (from over 115 millions to 107 millions approximately), which signals some type of economic crisis.