Answer: D. fall and the equilibrium quantity to stay the same.
Explanation: Price elasticity of supply is simply the responsiveness of change in quantity supplied to a change in price of a particular commodity or service. Elasticity of supply is of different types. We have inelastic supply, elastic supply, perfectly inelastic and perfectly elastic.
Perfectly inelastic supply means the supply curve is vertical. There is not going to be any change in quantity supplied despite change in demand but only the price moves. So, if there is a reduction in demand, the equilibrium price will definitely fall while the quantity supplied remains the same.