Which of the following markets has a single firm?

In the figure above, the economy is at an equilibrium with real GDP of $16 trillion and a price level of 110. As the economy moves toward its ultimate equilibrium, the ________ curve shifts ________

A) aggregate supply; leftward B) aggregate supply; rightward C) aggregate demand; rightward D) aggregate demand; leftward E) potential GDP; leftward

Calculate the elasticity of supply when an increase in demand causes the equilibrium price and quantity to change from $2.00 and 500 to $2.80 and 1,000, respectively