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:

Group of answer choices

Default risk and liquidity differences

Tax effects

Inflation differences

Real risk-free rate differences