Which of the following is true of the price elasticity of demand of a product?

a. It measures the responsiveness of quantity demanded or quantity supplied to a change in one of the determinants of demand and/or supply.
b. It is calculated as the percentage change in the quantity demanded of the product divided by the percentage change in the price of the product.
c. It is calculated as the percentage change in the demand for the product divided by the percentage change in income of a consumer, everything else held constant.
d. It measures the responsiveness of demand to a change in the quantity supplied.
e. It is calculated as the percentage change in the quantity demanded of the product divided by the percentage change in the price of a related product, everything else held constant.

b