An increase in the price of hot dogs from $1.60 to $2.00 per pound increased the average number of hamburgers demanded per capita per week from 1 to 1.4. assuming that all other economic variables were held constant, the arc cross-price elasticity of demand between hot dogs and hamburgers is

a. –1.5, which indicates that the two goods are substitutes.
b. 1.5, which indicates that the two goods are complements.
c. 1.5, which indicates that the two goods are substitutes.
d. –1.5, which indicates that the two goods are complements.