Final answer:
When the price of a good or service changes,(b.) the demand curve shifts in the opposite direction. A movement along a given supply curve occurs when there is a change in the quantity supplied due to a change in price.
Step-by-step explanation:
When the price of a good or service changes, the demand curve shifts in the opposite direction. This means that as the price increases, the quantity demanded decreases, and vice versa. On the other hand, a movement along a given supply curve occurs when there is a change in the quantity supplied due to a change in price, while other factors affecting supply remain constant.