According to top rating agencies S&P double-B and other lower grade bonds are classified as

development bonds
junk bonds
compounded bonds
discounted bonds

The correct answer is: B. junk bonds.

Junk bonds are bonds that are considered to be high-risk investments. They are often issued by companies that are in financial difficulty or have a history of defaulting on their debt. Junk bonds typically have higher interest rates than investment-grade bonds, which reflect the higher risk of default.

Development bonds are bonds that are issued by governments or government agencies to finance economic development projects. These bonds are typically considered to be low-risk investments, and they often have lower interest rates than other types of bonds.

Compounded bonds are bonds that pay interest on both the principal and the interest that has already been earned. This type of bond can be more profitable than a simple interest bond, but it also carries more risk.

Discounted bonds are bonds that are sold at a price that is lower than their face value. This means that the investor will earn a higher return on their investment, but they will also have to wait longer to receive their full investment back.

In conclusion, the correct answer is B. junk bonds.