Answer:
The differences in the rates among these bonds is the difference in their credit risks. The T-Bond is a bond backed by the government which means it has no chances of defaulting therefore it has the lowest interest rate, as investors are willing to receive less interest for a T - Bond because it is least likely to default. On the other hand the other 3 bonds are rated and the best rated is AAA followed by A and the last BBB, the higher the rating the less likely the bond is to default, so the AAA bond has to pay less interest than A because it is less likely to default.
Explanation:
