Final answer:
Demand curves are ranked from most inelastic to most elastic based on their price elasticity of demand, with elastic demand having an elasticity greater than one, inelastic less than one, and unitary elasticity exactly one.
Step-by-step explanation:
To rank five demand curves in terms of elasticity, we need to look at the price elasticity of demand for each curve. The price elasticity of demand essentially measures the responsiveness of the quantity demanded to a change in price. By definition, elasticity greater than one is considered elastic, which indicates a high responsiveness to price changes. Elasticity less than one is considered inelastic, showing low responsiveness. An elasticity of exactly one is known as unitary elasticity, which means that the quantity demanded changes proportionately with price.
To rank the curves, one would list them from the lowest elasticity value (most inelastic) to the highest elasticity value (most elastic). Any curve with higher elasticity than another for any given quantity can indeed be considered more elastic. Since the given information mentions that the demand elasticities are already listed in order of increasing elasticity, the ranking would follow the same order presented in Table 5.2.