Which of the following defines a luxury good?

A luxury good is characterized as a normal good that takes up a greater proportion of income as income increases. This definition highlights that luxury goods are not just desired for their utility but are also perceived as indicators of wealth and status. As consumers' incomes rise, they tend to spend a higher percentage of their income on these goods due to the enhanced demand for products that offer superior quality, exclusivity, or brand prestige.

In contrast, essential goods are fundamental for survival and generally are consumed regardless of income changes, while inferior goods are those for which demand falls as income rises. Lastly, the idea of a good being universally affordable regardless of income doesn't align with the concept of luxury goods, which are defined not by their affordability but rather by their exclusivity and higher price point relative to a consumer's budget.