The Effects of the Negative Supply Shocks of 1973,1979 and 2007

The effects of the negative supply shocks of 1973,1979 and 2007 were different due to the ________.

A) willingness of policy makers,in the earlier episodes,to cause a sharp increase in unemployment,in order to keep inflation low
B) coincidence,in 2007,of politically-motivated expansionary policies to lower unemployment
C) collapse of savings banks and real estate markets in the 1970s
D) need,in the earlier episodes,to resort to severely contractionary monetary policy