Europeans began exploring the North American continent during which century?

answer; (d) one tectonic plate plunges beneath another; (most common,convergent boundaries)

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.