单选题 It would be more effective to persuade the teenager smokers to give up smoking if ______.

A、 the schools showed more pictures of smokers' lungs to the teenager smokers
B、 the cigarette vending machines could be completely eliminated
C、 the federal excise tax on cigarettes would be further increased
D、 the teenager smokers would be convinced by their own fellow pupils

【正确答案】 D

【答案解析】这一题是紧扣着上一题的，应针对主要原因对症下药。