Which of these ensures that the U.S. government does not own the Fed?

The option stating that private national banks are required to purchase shares in the Fed is correct because it highlights the structural design of the Federal Reserve System. The Federal Reserve, as the central banking system of the United States, operates as an independent entity within the government but is not owned by it.

By requiring private national banks to buy shares in the Federal Reserve Banks, the system maintains a level of private ownership and influence in its operations, thus preventing government ownership. This means that while the Federal Reserve operates in the public interest and under some governmental oversight, the financial backing and governance are tied to private financial institutions rather than direct governmental control. This hybrid model serves to provide both stability and independence, ensuring that the government does not exert direct ownership or control over monetary policy decisions.

In contrast, other options either inaccurately describe the structure of ownership or misinterpret the relationship between the Federal Reserve and the banks, failing to recognize the essential role that private national banks play in the funding and governance of the Federal Reserve System.