Assume that interest rates on 20-year treasury and corporate bonds with different ratings, all of which are noncallable, are as follows:

t-bond = 7.72%
a = 9.64%
aaa = 8.72%
bbb = 10.18%

the differences in rates among these issues were most probably caused primarily by:

answer

a. real risk-free rate differences.
b. tax effects.
c. default risk differences.
d. maturity risk differences.
e. inflation differences.