Correct Answer: An inferior good.

Solution : The correct answer is (b) an inferior good.

Inferior goods are goods for which demand decreases as income increases. When the income elasticity of demand for a good is negative, it indicates that as people's income rises, they tend to consume less of that particular good and switch to higher-quality alternatives. Examples of inferior goods may include generic or store-brand products, lower-quality goods, or lower-priced alternatives.