What Was the Chain of Events That Occurred 2008-2009 When

What was the chain of events that occurred 2008-2009 when the U.S. "housing bubble collapsed"?

A) Home prices rose out of the reach of households; home sales fell; and banks were left with no borrowers for their excess reserves, creating a crisis for banks.
B) Savings increased, leading to less investment in homes; a lower demand for homes caused drops in home prices, which led to unemployment in the construction industry.
C) Home values fell below mortgage values; homeowners defaulted on these loans, causing losses to financial firms, investors, and banks.
D) Banks foreclosed on mortgage loans, which caused housing prices to drop, which led to interest rates rising so that homes became unaffordable.