Concept:An increase in demand with supply unchanged raises both equilibrium price and quantity.
Explanation:When demand rises, the demand curve shifts to the right.
At the old equilibrium price, buyers now want more than suppliers are willing to sell.
This excess demand pushes the price upward.
As the price rises, producers increase the quantity supplied along the existing supply curve.
The new equilibrium is reached at a higher price and a higher quantity.
Therefore, equilibrium price
P and equilibrium quantity
Q both rise.
Answer:D. rise