If potential gdp is equal to​ $600 billion, what does the longminus−run aggregate supply curve look​ like?
a. it is a vertical line at a level of gdp above​ $600 billion.
b. it is a horizontal line at​ $600 billion of gdp.
c. it is a vertical line at​ $600 billion of gdp.
d. it is a vertical line at a level of gdp below​ $600 billion.