单选题 When mentioning the California Department of Health Service's efforts in placing antismoking commercials on television, including popular MTV programs, the writer hinted that ______.

A、 the proportion of adolescent tobacco users has dramatically decreased
B、 many adolescent smokers are successfully persuaded in giving up smoking
C、 some teenagers develop the habit of smoking rather than taking weed because cigarettes are relatively cheaper
D、 teenager smokers are quite certain about the effectiveness of the antismoking campaign

【正确答案】 D

【答案解析】此题可用排除法。A，B两项明显不对，C项与题意无关，只有D项，因为青少年们确定这些禁止吸烟的运动不会有什么效果。