Answer:
b. -2
Explanation:
Use following formula to calculate price elasticity of demand
Price Elasticity of demand = Change in Demand Quantity / Change in price
Price Elasticity of demand = (19,000 - 21,000) / (0.55 x 19,000 - 0.45 x 21,000)
Price Elasticity of demand = -2,000 / 1000
Price Elasticity of demand = -2
So, the correct option is b. -2