(4) Consumer's preference Explanation: The Law of Demand states that, all else being equal, as the price of a product increases, quantily demanded lowers; likewise, as the price of a product decreases, quantity demanded increases. Demand is derived from consumers’ tastes and preferences, and it is bound by income. In other words, given a limited income, the consumer must decide what goods and services to purchase. Each consumer will purchase different things because individual preferences and incomes differ.