单选题 An analyst does research about price elasticity of demand and determines that when the price of a product increases from $15 to $17, the quantity demanded decreases from 51 units to 45 units. The product's price elasticity of demand is best described as:
A. inelastic.
B. unit elastic.
C. elastic.

【正确答案】 B
【答案解析】[解析] 本题考查的是需求价格弹性(price elasticity of demand)的基本公式。只需要将数值代入以下公式即可。