Questions: Why did the U.S. dollar became important to economies around the world in the mid-20th century? A. Businesses were required to use U.S. dollars when buying foreign goods. B. Countries began tying the value of their currency to the U.S. dollar. C. Most countries replaced their own currency with the U.S. dollar. D. The U.S. dollar was the first example of a government creating a fiat currency.

The answer is B. Countries began tying the value of their currency to the U.S. dollar.

This option is incorrect because businesses were not universally required to use U.S. dollars for international trade. While the U.S. dollar was widely used, it was not a mandatory requirement for all international transactions.

This option is correct. After World War II, the Bretton Woods Agreement established the U.S. dollar as the world's primary reserve currency. Many countries pegged their currencies to the U.S. dollar, which was itself convertible to gold. This system helped stabilize exchange rates and facilitated international trade and investment.

This option is incorrect because most countries did not replace their own currencies with the U.S. dollar. Instead, they maintained their own currencies but pegged their value to the U.S. dollar.

This option is incorrect because the concept of fiat currency existed long before the mid-20th century. The U.S. dollar became a fiat currency after the end of the Bretton Woods system in 1971, but this was not the reason for its importance in the mid-20th century.