Final answer:
According to the law of demand, people are more likely to choose a substitute instead of their usual product when the substitute's price is lower, making it more economically appealing.
Step-by-step explanation:
According to the law of demand, people are most likely to choose a substitute instead of their usual product when the substitute's price is lower. This lower price makes the substitute more attractive as it offers a similar utility or function at a reduced cost. The law of demand indicates that as the price of a good decreases, the quantity demanded for it increases. Consequently, a lower price for a substitute can decrease demand for the original product. For instance, the increase in demand for tablet computers due to their falling prices has led to a decrease in demand for laptops, graphically represented by a leftward shift in the demand curve for laptops.