Match the items of List-I with the items of List-II and indicate the correct answer.

List-I	List-II
a. Absolute cost advantage theory	1. The empirical evidence based on US export of labour-intensive goods challenging the factor endowment theory.
b. Comparative cost advantage theory	2. A country with a direct cost advantage in the production of a product on account of greater efficiency.
c. Factor endowment theory	3. A country should produce and export a commodity that primarily involves a factor of production in abundance within the country.
d. Leontief paradox	4. A country should specialize in the production and export of a commodity in which it possesses the greatest relative advantage.