Final answer:
An increase in demand causes the demand curve to shift to the right, indicating that consumers are willing and able to purchase more at any given price point.
Step-by-step explanation:
When there is an increase in demand, the entire demand curve on a graph visually representing the market for a good or service will shift. This shift signifies that consumers are willing and able to purchase more of the product at every price point than before. According to standard economic theory, the correct response to an increase in demand is that the demand curve will shift to the right. Conversely, if demand decreases, the curve shifts to the left, indicating that consumers are willing and able to purchase less at any given price. The slope of the demand curve is not affected by an increase or decrease in demand; it only impacts the position of the curve on the graph. Therefore, the answer to the student's question is that an increase in demand causes the demand curve to shift to the right.