参考答案

正确答案：B
解析：How did green advertisements change after the first wave?
[A]和[B]的意思相矛盾，根据命题规律，这类选项中往往有一个是答案。再根据文中提到的 In 1992 the Federal Trade Commission established guidelines for green marketing，followed shortly by state governments可知，绿色广告在第一次浪潮后受到了更严格的监管，故答案为[B]。