Which of the following situations is an example of reinvestment risk
a. After interest rates decreased, issuers called their bonds back and issued new bonds with lower interest rates. For bond investors to realize the same return on new bonds, they are forced to purchase lower quality bonds.
b. An individual purchased a security that ultimately yielded significantly less than another that he could've chosen.
c. A bond issuer is having financial difficulties and is unable to make interest and principal payments on its debt.
d. The payments on mortgage-backed securities are ending early due to homeowners refinancing the mortgages as interest rates fall.