Question

a consumer might respond to a negative incentive by
purchasing more of the products.
buying the good at a cheap price
receiving a discount
decreasing use of the product to save money.

Explanation:

A negative incentive discourages a behavior. Purchasing more (first option) or buying cheap/receiving discount (second/third) are positive or neutral incentives. Decreasing product use to save money (fourth option) is a response to a negative incentive (like a price increase or tax) that makes the product less desirable, so consumers cut use to save.

Answer:

D. decreasing use of the product to save money (assuming the options are labeled A - D with A as "purchasing more of the products", B as "buying the good at a cheap price", C as "receiving a discount", D as "decreasing use of the product to save money")