Correct Option: C. A decrease in consumer preferences for the good Detailed Explanation: To understand why option C is the correct answer, we need to delve into the concept of demand and the factors that influence it. Demand for a good refers to the quantity of that good that consumers are willing and able to purchase at various prices, holding all other factors constant (ceteris paribus).

1. Normal Goods: Normal goods are those for which demand increases as consumer income rises, and conversely, demand decreases when consumer income falls. However, the question specifically asks about factors that would cause a decrease in demand, not just changes in income.
2. Consumer Preferences: A decrease in consumer preferences for a good means that consumers no longer value the good as highly as they did before. This could be due to various reasons, such as changes in trends, the introduction of better alternatives, or negative publicity about the product. When consumer preferences decline, the demand for that good will decrease, as fewer consumers are willing to buy it at any given price.
3. Analyzing the Other Options:
4. A. An increase in consumer income: This option would typically lead to an increase in demand for normal goods, not a decrease. When consumers have more income, they are more likely to purchase more of a normal good, as they can afford it.
5. B. A decrease in the price of a substitute good: Substitute goods are those that can replace each other. If the price of a substitute good decreases, consumers may choose to buy more of that substitute instead of the original good, leading to a decrease in demand for the original good. However, this is not as direct a cause of decreased demand as a change in consumer preferences, which fundamentally alters how much consumers value the good.
6. D. An increase in the price of a complementary good: Complementary goods are those that are used together (e.g., printers and ink). If the price of a complementary good increases, it may lead to a decrease in demand for the original good, but this is contingent on the relationship between the two goods. While this can decrease demand, it is not as direct as a change in consumer preferences.

Summary of Key Points:

• Demand for normal goods increases with higher income and decreases with lower income.
• Consumer preferences are a critical factor in determining demand; a decrease in preference directly leads to a decrease in demand.
• Substitutes and complements can influence demand, but their effects are often indirect and depend on price changes rather than fundamental shifts in consumer attitudes.

Revision Summary:

• A decrease in consumer preferences for a good leads to a direct decrease in demand.
• Normal goods see increased demand with rising income and decreased demand with falling income.
• Price changes in substitutes and complements can affect demand but are not as straightforward as changes in consumer preferences.
• Understanding the relationship between consumer preferences and demand is crucial for analyzing market behavior.