Final answer:
C. Wright Mills argued that institutional centralization occurred in the political, military, and economic sectors during the 20th century.
Step-by-step explanation:
In his book The Power Elite, C. Wright Mills argued that during the course of the 20th century, a process of institutional centralization occurred in the political sector, military sector, and economic sector. This means that power and control became concentrated in these areas, with a small group of wealthy and influential people at the top of society holding all the power and resources.