The second alternative is correct (B).
Countries usually adopt customs tariffs to protect domestic producers from foreign competition. However, in the long term, this policy has proved to be inefficient, because by inhibiting competition, this policy encourages production models that are inefficient and deprives consumers of access to goods and services at a lower cost.
Consequently, nations lose the market they could achieve if there were free trade. Thus, international trade between countries tends to decline.
