One reason is that Americans view business as being more firmly based on the ideal of competition than other institutions in society. Since competition is seen as the major source of progress and prosperity by most Americans, competitive business institutions are naturally respected.
【正确答案】：
由于大多数美国人都把竞争视为进步与繁荣的主要来源，具有竞争性的商业机构也就理所当然地受到他们的尊重。 
【题目解析】：由于大多数美国人都把竞争视为进步与繁荣的主要来源，具有竞争性的商业机构也就理所当然地受到他们的尊重。 注意since,be seen as（被看做是......）的用法及翻译。