The correct answers are A and B.
Free trade seeks to eliminate barriers to imports and promote international trade. Yet it can be more than dangerous to the environment. The main concern is the lowering of national environmental standards in order to export more goods. With free trade, large amount of goods are transported every day which contributes to the rise of the carbon footprint of transportation. Increased production on agricultural farms means more pesticide use and more consumption of energy, all harmful to the environment.
Trade barriers can have a negative effect on the developing world ( overproduction and dumping ) but they do help 'infant industries'. Protective tariffs and trade barriers protect brand-new industries from foreign and national competition. This gives the new companies a bit more time to establish their position on the market.