Answer:
D) An increase in the demand for one will usually result in an increased for the other.
Step-by-step explanation:
Complementary goods are products or services that are used in conjunction with the other. For example, If you buy a car, surely you must purchase petrol. Car and petrol are therefore complementary goods. They are used jointly.
Demand for complementary goods can be described as joint demand. It tends to fall or rises in unison. If the demand of one increases, the demand for the other one also rises. Should the demand for cars goes up; it means more petrol will be demanded. Computers hardware and software are complementary goods as they have to be used together. If the demand for computers hardware increase, then the demand for computer software goes up.