[A] The law states that as a firm increases the input of one factor of production while keeping other inputs constant, the resulting increase in output will eventually diminish.

[B] The law states that for certain inferior goods, as the price of the good increases, the quantity demanded also increases.

[C] The law states that individuals, firms, or countries should specialize in producing goods or services for which they have a lower opportunity cost compared to others.

[D] The law states that as household income increases, the proportion of income allocated to food expenditure decreases, while the proportion allocated to other goods and services, such as housing, transportation, increases.