Vodka and Whiskey Are Considered by Consumers to Be Substitutes

Vodka and whiskey are considered by consumers to be substitutes.The likely economic impact of a decrease in the price of whiskey is a:

A) movement up along the demand curve for vodka.
B) movement down along the demand curve for vodka.
C) decrease in the supply of whiskey.
D) rightward shift of the demand curve for vodka.
E) leftward shift of the demand curve for vodka.