A Unit Elastic Demand

A unit elastic demand

A) means that the ratio of a change in quantity demanded to a change in price is equal to 1.
B) means that the ratio of a percentage change in quantity demanded to a percentage change in price is equal to 1.
C) means that the ratio of a change in price to a change in quantity demanded is equal to 1.
D) is illustrated by a horizontal demand curve.
E) is illustrated by a vertical demand curve.