After a Period of Price Stability in the 1990s, Housing

After a period of price stability in the 1990s, housing prices increased dramatically during 2002-2005 because

A) regulations designed to make housing more affordable increased the demand for housing and drove housing prices upward.
B) regulations designed to make housing more affordable decreased the number of sub-prime loans and made home buying a safer investment.
C) mortgage lending standards tightened, and therefore mortgage loans for housing were only available to buyers purchasing highly expensive homes.
D) home buyers were putting more money down and requiring more return on their investment, driving housing prices up.