Which term describes a good that is used or consumed jointly with another product and has greater value when paired with its complement?

• A. Supply
• B. Demand
• C. Substitute Good
• D. Complementary Good

Answer: (D)

Complementary goods are those that are typically used together, and their value increases when paired with their partner. A printer and ink cartridges are a classic example: the printer is much more useful when you have ink, and ink cartridges become more desirable because they work with the printer. Because these goods are linked in consumption, they tend to rise in value together, and changes in the price or availability of one affect the demand for the other (negative cross-price elasticity). This is different from substitutes, which can replace each other in use, so a price rise in one boosts demand for the other. It’s also not about how much producers are willing to supply at various prices—that’s a different concept. So the term that fits the description is complementary good.