单选题According to the passage, the scientists carried out their researches on ______.A smokers from different parts of the worldB smokers from different states in the United StatesC actors and actresses who smoke a lotD wait staff and bartenders

题目
单选题
According to the passage, the scientists carried out their researches on ______.
A

smokers from different parts of the world

B

smokers from different states in the United States

C

actors and actresses who smoke a lot

D

wait staff and bartenders


相似考题
参考答案和解析
正确答案: C
解析:
推断题。答案来自第一段最后:…nonsmokers working in bars and restaurants in the state.由此可知其实验对象为酒吧与餐厅的侍者,答案为D。