Answer:
D. a and b.
Step-by-step explanation:
Economic agent is defined as a person that makes decisions. Choices are made to better drive business objectives.
In a. above, consumers prefer to rent more kayaks from a vendor that is giving them at lower prices. The consumer is the decision-maker, while the incentive is lower prices.
In b. the department stores make the decision not to install security cameras (which are quite expensive) instead they increase security guards. The incentive here is that of comparably lower cost. It is less costly to have goods shoplifted than to install the cameras.