Final answer:
Choice D, which presents data about population changes, is the detail in the fifth paragraph that supports the main fact regarding the urbanization of the United States due to technological improvements.
Step-by-step explanation:
Details Supporting the Main Fact
The fifth paragraph of the provided text discusses the rural to urban shift in population due to the Industrial Revolution. The details supporting the main fact revolve around the growth in American urban areas and the technological advancements that spurred urbanization. Among the multiple choice options given, choice D, which mentions data about population changes, directly supports this main fact. The historical data and trends mentioned provide a metric to understand the scale and speed at which urbanization occurred, illustrating the drastic increase in the number of cities with more than 10,000 residents and the percentage of U.S. residents living in urban areas from 1820 to 1860.