Some analysts suggest that inner-city riots have frequently occurred when poor people realize that their chances of climbing out of poverty are unlikely because of the structure of our social system. Their frustration is based on their perception that they are living in a(n) .

closed stratification system.                          

Explanation:

Social stratification system is defined as a system through which a particular society tends to rank different categories of individuals hierarchically. Therefore, the stratification system is considered as either open or closed.

Closed stratification system: It is referred to as a system that allows a very little change or alteration in the "social position". In other words, it states that an individual gets a little or no chance of moving towards another level in a particular society and therefore a person in the same society or place where he or she has been born.

In the question above, the given statement signifies the "closed stratification system".

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.