Consider the Following Multiplicative Demand Function Where Q_D = Quantity

Consider the following multiplicative demand function where Q_D = quantity demanded, P = selling price, and Y = disposable income:Q_D = 1.6P ^{- 1.5}Y² The coefficient of Y (i.e., .2) indicates that (all other things being held constant) :

A) for a one percent increase in disposable income, quantity demanded would increase by .2 percent
B) for a one unit increase in disposable income, quantity demanded would increase by .2 units
C) for a one percent increase in disposable income quantity demanded would increase by .2 units
D) for a one unit increase in disposable income, quantity demanded would increase by .2 percent
E) none of the above