The answer is letter A. The Clear Air Act would be a reason for the Environmental Protection Agency or EPA to regulate car emissions. EPA sets the emission standards under the said rule or regulation and this also covers the green house gas emissions.
The main relationship between social stratification and social mobility is that social stratification is the way people are ranked and ordered in society, while social mobility is the movement of individuals through a system of social stratification.
<h3>Social Mobility</h3>
Social mobility is the movement of an individual or group from one social position to another over time.
Therefore, the main relationship is the fact that when there is upgrade in one's social status (upward mobility), i.e. more income, it changes one's social class (social stratification).
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The river made rich soil which allowed for them to plant crops
