Correct Option: D

Price elasticity of demand measures consumer response to price changes. If consumers are relatively sensitive to price changes, demand is elastic; if they are relatively unresponsive to price changes, demand is inelastic. Perfectly inelastic demand is graphed as a line parallel to the vertical axis; perfectly elastic demand is shown by a line above and parallel to the horizontal axis. When the demand for a commodity is perfectly elastic, the quantity of demand keeps changing with the price. So the coefficient of price elasticity of demand is infinity.