If the price of textbooks increases by one percent and the quantity demanded falls by one-half percent, then the price elasticity of demand is equal to:

If the price of textbooks increases by one percent and the quantity demanded falls by one-half percent, then the price elasticity of demand is equal to:
A.0.5.
B.5.
C.2.
D.0.05.
正确答案：0.5.