The preconditions for the $2008-2009$ financial crisis were complex and$-$caused by the interaction of which of the following factors?

a$.$ Enactment of the Community Reinvestment Act which attempted to eliminate bank "redlining" of poor neighborhoods

b$.$ The repeal of the Glass$-$Steagall Act of $1933$ which had placed restrictions on the activities that commercial banks and investment banks $($or other securities firms$)$ could engage in$.$ It effectively separated those activities, so the two types of business could not mix, in order to protect consumer's deposits from speculative use.

c$.$ Enactment of the Commodity Futures Modernization Act which exempted credit default swaps and other derivatives from regulations.

d$.$ All of the above