Final answer:
The income elasticity of demand for an inferior good is negative.
Step-by-step explanation:
An inferior good is a type of good for which demand decreases as income increases. In other words, when people have more income, they tend to buy fewer of these goods. The income elasticity of demand for an inferior good is negative. This means that as income increases, the quantity demanded for the inferior good decreases.
For example, let's say a person's income increases and they decide to buy fewer generic brand clothes and more designer brand clothes. In this case, generic brand clothes are the inferior good because the quantity demanded decreases as income increases. The income elasticity of demand for generic brand clothes would be negative.
Therefore, the correct answer is b. negative.