The demand curve for a product is given by the equation Q d = 22 – 0.2P When the price of the product is $10, the price – elasticity of demand is:

The demand curve for a product is given by the equation Q d = 22 – 0.2P

When the price of the product is $10, the price – elasticity of demand is:

A. – 0.1

B. – 2.5

C. – 4.5

D. – 5.0   

Explain your answer.