When the Price of Pencils Decreases from $3 to $1,the

Multiple Choice

When the price of pencils decreases from $3 to $1,the quantity demanded increases from 100 to 200 pencils.By the midpoint method,the price elasticity of demand equals:

A) 0.17.
B) 0.5.
C) 0.67.
D) 1.5.