A) embargo is the correct answer. Embargo refers to the ban on trade with a particular country as a punishment for policies or acts of the embargoed country. The target country would not be able to make any form imports to other country who give the embargo (a trade war can occur).
Trade barriers are government-induced restrictions on international trade (the imposition of some sort of cost on trade that raises the price/availability of the traded products). The barriers can take the forms of "Tariffs" and "Non-tariff barriers to trade" (embargo).
