A、American industrialists. B、French economists. C、International leaders. D、Civil War veterans. B结合短文前两句可知，Their motto was laisse

In the 18th century French economists protested the excessive regulation of business by the government. Their motto was laisser faire. Laisser faire means let the people do as they choose. In the economic sense, this meant that while the government should be responsible for things like maintaining peace and protecting property rights, it should not interfere with private business. It shouldn’t create regulations that might hinder business growth, nor should it be responsible for providing subsidies to help. In other words, governments should take a hands off approach to business. For a while in the United States, laisser faire was a popular doctrine. But things quickly changed. After the Civil War, politicians rarely opposed the government’s generous support of business owners. The were only too glad to support government land grants and loans to railroad owners, for example. Their regulations kept tariffs high and that helped protect American industrialists against foreign competition.  Ironically in the late 19th century, a lot of people believed that the laisser faire policy was responsible for the country’s industrial growth. It was generally assumed that because business owners did not have a lot of external restrictions placed on them by the government, they could pursue their own interests, and this was what made them so successful. But in fact, many of these individuals would not have been able to meet their objectives if not for government support.