问题如下：
A decrease in a country’s total imports is most likely caused by:
选项：
A.an increase in the pace of domestic GDP growth.
B.a cyclical downturn in the economies of primary trading partners.
C.persistent currency depreciation relative to primary trading partners.
解释：
C is correct.
When a nation’s currency depreciates, domestic goods seem cheaper than foreign goods, placing downward pressure on demand for imports. When the depreciation persists for some time, the country’s total imports are likely to decrease.
考点：Resource Use Through The Business Cycle
解析:如果一国GDP高速增长，那么该国居民的消费会随之增加，这会导致该国进口的增加而非下降，所以A选项说法错误。
A国贸易对手国经济不景气并不会影响A国的总需求和进口情况，所以B选项说法错误。
如果一国货币持续贬值，那么国外的商品用本币计价表示会越来越贵，这会导致本国居民减少对外国商品的购买，进口下降，所以C选项是正确的。
请问为什么B里的primary trading partner是对手方而C的primary trading partner就是指本国呢，如何判断是哪一方呢，谢谢
