On a graph, when demand decreases, the demand curve shifts to the left. Which of the following best explains this shift?

• A. The supply of the good has increased.
• B. The price of the good has increased, causing a movement along the demand curve.
• C. Consumers are willing to buy less of the good at every price.
• D. There is an increase in consumer income for a normal good.

Answer: (C)

Verified step by step guidance

1. Understand the difference between a movement along the demand curve and a shift of the demand curve. A movement along the demand curve happens when the price of the good changes, affecting quantity demanded, but the demand curve itself does not move.
2. Recognize that a shift of the demand curve means that at every price, the quantity demanded changes. This can be caused by factors other than the price of the good, such as changes in consumer preferences, income, or prices of related goods.
3. Analyze the options given: an increase in supply affects the supply curve, not the demand curve; a price increase causes movement along the demand curve, not a shift; an increase in consumer income for a normal good typically shifts demand to the right (increase), not left.
4. Identify that a decrease in demand (shift to the left) means consumers are willing to buy less of the good at every price, which matches the explanation that 'Consumers are willing to buy less of the good at every price.'
5. Conclude that the best explanation for a leftward shift in the demand curve is a change in consumer behavior or preferences that reduces demand at all prices, not a change in price or supply.