7. Explain whether the following events would increase, decrease, or have no effect on the short-run aggregate supply curve:

a. A tornado damages factories in Wisconsin and Minnesota.

b. Because of expectations of a booming economy, auto companies invest in more efficient machinery and equipment.

c. New technologies result in declining prices of crude oil.

d. The United Steel Workers Union wins a large increase in wages from domestic steel companies.

e. Workers participate in retraining programs that enhance their productivity.