A percentage increase in the quantity demanded for Product A results in a percentage decrease in Product B. These products are known as ______ products.

A percentage increase in the quantity demanded for Product A results in a percentage decrease in Product B. These products are known as ______ products.

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

Answer: (D)

Substitutes are goods that satisfy similar needs, so buyers can switch between them. When demand for Product A increases, people tend to substitute A for Product B, causing the quantity demanded of B to fall. This inverse relationship—one rises while the other falls—signals that the two goods can replace each other in satisfying the same want. Complements, on the other hand, tend to move together in demand because they’re often used together, not in opposition. Normal and inferior describe how demand changes with income, not how two goods interact in substitution, so they don’t explain this pattern.

Substitutes are goods that satisfy similar needs, so buyers can switch between them. When demand for Product A increases, people tend to substitute A for Product B, causing the quantity demanded of B to fall. This inverse relationship—one rises while the other falls—signals that the two goods can replace each other in satisfying the same want. Complements, on the other hand, tend to move together in demand because they’re often used together, not in opposition. Normal and inferior describe how demand changes with income, not how two goods interact in substitution, so they don’t explain this pattern.