In the early 1960s, before the standard container became ubiquitous, freight costs were 10 per cent of the value of USimports, about the same barrier to trade as the average official government import tariff. - Option A is incorrect. From the 5th paragraph, option B is correct. It has not been mentioned that imports increased Option C is incorrect The weight of boxes were the real reason, not the size. Option D is wrong. Hence, option B is the correct answer