Many Lessons Should Be Learned from the Credit Crunch

Many lessons should be learned from the credit crunch.

A) One lesson is that credit rating agencies need to refine their models for evaluating esoteric credit risk created in MBS and CDOs.
B) One lesson is that borrowers must be more wary of putting complete faith in credit ratings.
C) One lesson is that bankers seem not to scrutinize credit risk as closely when they serve only as mortgage originators and then pass it on to MBS investors rather than hold the paper themselves.
D) all of the options