The List Below Refers to the Price Elasticity of Demand

The list below refers to the price elasticity of demand.
1) perfectly inelastic
2) perfectly elastic
3) unitary elasticity
4) elastic
5) inelastic
-Refer to the information above to answer this question.What is a demand curve that is parallel to the vertical axis?

A) 1.
B) 2.
C) 3.
D) 4.
E) 5.