As a rule, what's efficient in one place will be efficient in most other places, thus American businesses are fierce competitors ______ they choose to sell their product, having been formed in a competitive environment that breeds optimality.
 
【正确答案】 C
【答案解析】 句意：无论选择何处作为产品销售地，美国商业都是强有力的竞争者，因为它们在竞争性强的环境下获得了最优性。wherever引导地点状语从句。