Which of following is a non-tariff barriers are used by the countries to discourage firms to import or export some products? A. Imposing import and export quotas with effect to volume of transactions or determining the time frame for import-export operations. B. By encouraging international transactions without any restrictions. C. Increacing tariff on the selected product(s) by imposing high cross-boarder taxes. D. Encouraging local firms to increase prices on selected product(s)