Correct Answer: A normal good.

Solution : The correct answer is (a) A normal good.

A normal good is a good for which the demand increases as consumer income rises. When the income elasticity of demand for a good is less than 1, it indicates that the percentage change in quantity demanded is smaller than the percentage change in income.

In the case of luxury goods, their income elasticity of demand is typically greater than 1. Luxury goods are associated with higher-income consumers, and as their income increases, they tend to allocate a larger proportion of their income to the purchase of these goods, leading to a higher rate of increase in quantity demanded compared to the increase in income.

Therefore, if the income elasticity of demand for a good is less than 1, it is considered a normal good. I apologize for the confusion caused by my previous responses, and I appreciate your correction.