Step-by-step explanation:
Basically, when people are more worried about the health risks of eating candy, they're less likely to buy it. This causes the demand curve to move to the left of D2 from D1, meaning that at any price point, people are more willing to buy less candy. To see this in action, let's look at the demand curve for candy. The original demand curve is D2, which shows people wanting to buy 10 bars at $1 per bar. But when people start worrying about their weight, they're less willing to buy the same amount, so the new demand curve is D1, which shows consumers only wanting to buy 8 bars. This is because the demand curve changes when people change their preferences, not when there's a change in supply.