The longer the time horizon, the higher the incidence of default for a given rating. This effect:
A.  is stronger for high-rated bonds than for low-rated bonds.
B.  is stronger for low-rated bonds than for high-rated bonds.
C.  is equal for low-rated and high-rated bonds.
D.  has not been studied enough to be documented.
Answer:B
There is a very strong increase of defaults over time for low-rated bonds. High-rated bonds tend to have much more stable rates of default over time.