Correct Answer: A normal good.

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

If the income elasticity of demand for a good is positive, it means that the quantity demanded of the good increases as income increases. Normal goods are goods for which demand increases with an increase in income. These goods are considered typical or regular consumer goods, and as consumers' income rises, they tend to spend more on these goods.

On the other hand, inferior goods have a negative income elasticity of demand, meaning that demand for these goods decreases as income increases. Inferior goods are typically lower-quality or less-desirable alternatives to other goods and are often associated with lower-income households.

Luxury goods, while often associated with higher income levels, can have a positive income elasticity of demand as well. However, it is important to note that not all goods with a positive income elasticity are luxury goods, as there can be normal goods that are not considered luxury items.