In Events Leading to the Housing Bubble, the Credit-Rating Agencies

In events leading to the housing bubble, the credit-rating agencies rated the assets associated with the housing market proper:

A) mid-level ratings indicating moderate risk, but were ignored.
B) AAA ratings indicating low risk, but turned out to be a right judgment.
C) AAA ratings indicating low risk, and turned out to be too optimistic.
D) mid-level ratings indicating moderate risk, and turned out to be too pessimistic.