A Model That Envisions No Short-Run Trade-Off Between Inflation and Unemployment

A model that envisions no short-run trade-off between inflation and unemployment can explain recession only in terms of

A) increases in aggregate demand.
B) decreases in aggregate demand.
C) an increase in the number of people looking for work without a corresponding increase in the number of jobs.
D) sudden surges in investment that cause the capital stock to increase too quickly.
E) none of the above.