Answer:
According to the risk of default from lowest to highest:
1. U.S. Treasury bonds.
2. Corporate bonds.
3. Junk bonds
Explanation:
Bonds are ways through which a governments and corporations are able to raise money in-order to finance the big projects.
It is issued to the public through a mapped out auction based in months or years validity. And, by buying a bond, you're giving the issuer a loan, and they agree to pay you back the face value of the loan on a specific date, and to pay you periodic interest payments.