The graph shows how the mass of copper changes as the volume of the element changes and the density remains constant. Which of these best represents the rate of change in the mass of copper with respect to the volume?.

The correct answer is b, social stratification is needed for a society to exist. marxist theory regarding social stratification is that due to the differing economic capacities among people in society, a natural separation occurs between those that own the means of production and those that sell their labour in the production chain. 

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