Concept:An increase in demand with unchanged supply shifts the demand curve rightward, causing a higher equilibrium price and a higher equilibrium quantity.
Explanation:Initially, the market is at equilibrium where quantity demanded equals quantity supplied.
When demand increases at the same supply, consumers now want more of the commodity at every price.
At the original price, this creates an excess demand or shortage.
Because supply is unchanged, the shortage pushes the price upward.
As the price rises, the quantity demanded falls slightly and the quantity supplied rises slightly along the existing supply curve.
This process continues until quantity demanded again equals quantity supplied.
The result is a new equilibrium at a higher price and a larger quantity traded.
Thus, both equilibrium price and equilibrium quantity increase.
Answer:A. increase