The united states shall guarantee to every state in this union a republican form of government, and shall protect each of them against invasion."–u. s. constitution

according to this quote, the job of protecting the nation from foreign enemies belongs to

the local governments

each state government

the national government

international governments

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.