Assume only liquidity risk and default risk impact the differences observed in bond yields. Additionally, assume credit rating agencies accurately assign credit ratings (which is a really big assumption like when we are talking about the mortgage crisis). Which of the following must be TRUE?

A The BBB bond has lower default risk than the A-rated bond

B If the spread over the US treasury for default risk is 1.4% for A-rated bonds, then the spread for liquidity is 0.6%

C The AAA-rated bonds trades more often than the AA-rated bonds

D If the spread for default risk is 1.4% for the A-rated bonds and the spread for default is 1.6% for the BBB-rated bonds, then this implies that the BBB-rated bonds trade more frequently than the A-rated bonds