Why Did Credit-Rating Agencies That Evaluated Mortgage-Backed Securities Have a Conflict

Why did credit-rating agencies that evaluated mortgage-backed securities have a conflict of interest?

A) Banks and other financial institutions were earning attractive fees creating and selling mortgage-backed securities.
B) Underwriters of mortgage-backed securities usually had little incentive to make sure that those who bought the securities would ultimately get paid.
C) Homeowners could shop around for the bank that offered the lowest mortgage rate.
D) Credit-rating agencies earned their fees by assessing the riskiness of these securities.
E) Investors found the yield on mortgage-backed securities attractive.