Human: Why is it that the U.S. dollar is the world's primary reserve currency? Assistant: 
The United States has the largest economy in the world, and the U.S. dollar is the most widely used currency in the world. This makes the U.S. dollar a natural choice for international trade and investment. Additionally, the U.S. government has historically been willing to support the value of its currency through foreign exchange interventions. These actions have helped maintain confidence in the U.S. dollar as a global reserve currency.