Other things the same, which of the following would both make foreigners more willing to engage in U.S. portfolio investment?

U.S. interest rates rise, the default risk of U.S. assets rise

U.S. interest rates rise, the default risk of U.S. assets fall

U.S. interest rates fall, the default risk of U.S. assets rise

U.S. interest rates fall, the default risk of U.S. assets fall