When the change in demand for one product negatively affects the demand for another product, those items are known as ______ products.

• A. Independent
• B. Substitute
• C. Complementary
• D. Inferior

Answer: (B)

Two goods that are used together show a negative impact on demand for the other when one product’s demand changes. In other words, if people demand less of one item, they’re also buying less of its partner because the pair is typically consumed together. This relationship is what economists call complementary goods. A classic example is printers and ink cartridges: if printer demand drops, ink cartridge demand tends to fall too, since fewer printers are being sold and used.

Independent goods have no predictable demand relationship—changes in one don’t affect the other. Substitutes are different: if one good becomes more desirable, demand for its substitute typically declines as people switch to the alternative. Lastly, inferior goods describe how demand responds to income, not how two products influence each other’s demand.