Final answer:
A movement down along a demand curve is caused by a rise in the price of the product.
Step-by-step explanation:
A movement down along a demand curve is caused by a rise in the price of the product. When the price of a product increases, consumers are less willing to buy it, resulting in a decrease in quantity demanded and a movement down the demand curve.
In contrast, a fall in the price of the product will cause a movement up along the demand curve, as consumers are more willing to buy the product at a lower price.