Final answer:
Karl Marx pioneered the Conflict perspective, focusing on the systemic inequalities and power struggles between the upper and lower classes that lead to societal tensions and change.
Step-by-step explanation:
The perspective that Karl Marx pioneered, which focuses on the friction between upper and lower classes, is C) Conflict perspective. This sociological approach examines how social structure, rather than individual personality characteristics, is responsible for common social issues like poverty and crime. Marx's conflict theory posits that societal conflict, especially in a capitalist society, arises as groups struggle to either attain wealth and power or to maintain existing hierarchies, inevitably leading to social change.
In contrast to the functionalist perspective, which sees societal institutions as necessary and beneficial to the social order, and the symbolic interactionist perspective, which explores social stratification on a micro-level through daily interactions, the conflict perspective centers on systemic inequalities and the power differential within groups. It is deeply concerned with how these disparities contribute to social tensions and ultimately to the transformation of society.