Which of the Following Is NOT True About So-Called Mortgage-Backed

Which of the following is NOT true about so-called mortgage-backed securities:

A) Before the crisis, they were believed by many banks to be a way of reducing loan risks
B) Before the crisis, they played a major role in broadening home ownership in America
C) They were linkages that spread instability across many financial institutions
D) Their use was strongly discouraged by the Federal government