Final answer:
The system of owning real property in the United States is capitalism, which allows for private ownership and control of property (C). Social mobility is highest in a meritocracy, where advancement is based on individual merits.
Step-by-step explanation:
The system of ownership of real property in the United States can best be described as capitalism. In a capitalist system, private citizens and corporations have the right to own and control property for personal or business purposes.
This is in contrast to systems like feudalism or socialism, where land and property rights are significantly different. In feudal societies, land ownership and power were primarily based on hierarchical systems with lords and vassals, with peasants working the land for protection and a place to live. Socialism, on the other hand, involves government ownership or control over basic resources and may limit private property to various extents.
Regarding social mobility, a meritocracy allows for the most social mobility among the given options, as it ideally bases advancement on individual talents and achievements rather than inheritance, class, or social status. Feudalism, monarchy, caste, and class systems generally offer less mobility as they tend to lock individuals into the social status they are born into.