Final answer:
The law of demand, a key concept in economics, states that there is an inverse relationship between the price of a good and the quantity demanded, assuming all other factors are constant.
Step-by-step explanation:
The law of demand is best described by the phrase, "The decline in the price of a good, holding everything else constant, leads to an increase in the quantity demanded." This fundamental economic principle expresses an inverse relationship between the price of a good or service and the quantity demanded. As prices decrease, consumers are generally more willing to purchase greater quantities. Conversely, if prices increase, the quantity demanded tends to fall. The law of demand assumes that all other factors influencing demand are held constant. For instance, when the price of gasoline rises, consumers may find ways to reduce usage which decreases the quantity demanded. This demonstrates the law of demand in action.