When the Price of Pencils Increases from $1

Multiple Choice

When the price of pencils increases from $1.50 to $2.50,there is an increase in quantity demanded of pens from 100 to 150.The cross-price elasticity of demand between pencils and pens is

A) 1.25.
B) 0.50.
C) 0.40.
D) 0.80.
E) 0.75.