Suppose a country has had a long run trend of rising prices and shrinking real gdp. to explain this in the as/ad model,
a. it is only necessary that long-run aggregate supply shifts left over time.
b. it is only necessary that aggregate demand shifts leftover time.
c. both aggregate demand and long-run aggregate supply must be shifting left.
d. none of the above cases would produce rising prices and shrinking real gdp over time.