Concept:An increase in supply with unchanged demand shifts the supply curve rightward, changing the market equilibrium.
Explanation:When supply increases, sellers offer more of the good at every price.
With demand constant, this causes an excess supply or surplus at the old price.
Sellers compete to clear the surplus, which pushes the price downward.
As the price falls, quantity demanded expands along the demand curve.
The new equilibrium is reached where the new supply curve meets the same demand curve.
At this new equilibrium, price is lower and quantity is higher than before.
Answer:D. falls and quantity rises.