Final answer:
The good in question is an inferior good.
Step-by-step explanation:
In the given scenario, the price of a good has increased from $6 to $24. To determine the nature of the good, we need to assess the relationship between its demand and income. If the demand for the good decreases as income increases, it is classified as an inferior good. In this case, as the price of the good has increased, it is likely that the demand for it will decline.
Therefore, the correct answer is c. An inferior good.