A、9-17. B、18-26. C、27-35. D、36-45. B 根据原文，最积极参与体育运动的是18至26岁的人。故答案是B。

W: Sam, could you review the results of the survey on leisure sporting activities again? We need to plan our proposal for tomorrow’s meeting.
M: Sure. I’ve summarized the results in the handout, broken down by consumer age groups and sporting activities. The survey was administered to 550 men and women between the ages of 18 and 55 years old The results have been compiled in the following age groups: 18 to 26, 27 to 35, 36 to 45, and 46 to 55. According to the results, the most active group involved in sporting activities are those between 18 and 26 years old, followed by those 36 to 45 years old.
W: Okay.
M: As far as particular sports are concerned, people in these two groups cited jogging as their favorite recreational sport followed by skiing, tennis, swimming, and cycling.
W: Hmm. Based on what you’ve said, I think we should consider targeting the 18 to 26 year-old age group more in the future. I also feel we should consider expanding our line of athletic shoes, particularly jogging and tennis footwear. We also have to come up with a more appealing slogan aimed at this age group.
M: I see what you mean. However, when these results are compared with the survey carried out three years ago, we can see a growing trend among older consumers-those 14, I mean 46 to 55-who are becoming more conscious and concerned about staving fit. I believe this trend will continue, so we should focus on this group instead.
W: I see your point. Well, let’s meet again on Wednesday to iron out more of the details of this proposal.