Final answer:
The law you're referring to is the law of diminishing marginal utility, which states that as a consumer consumes more units of a good, the marginal utility derived from each additional unit tends to decrease. Based on this law, a consumer will buy additional units of a product only if its price falls.
Step-by-step explanation:
The law you're referring to is the law of diminishing marginal utility. According to this law, as a consumer consumes more units of a good, the marginal utility they derive from each additional unit tends to decrease. In other words, each additional unit of a good provides smaller and smaller amounts of extra utility.
Based on the law of diminishing marginal utility, a consumer will buy additional units of a product only if its price falls.
This is because the diminishing marginal utility implies that the consumer values each additional unit of the good less and less. Therefore, a decrease in the price of the good makes it more attractive to the consumer and increases their willingness to buy more units.