B. a membership in a health club is a poor investment.
Feedback By stating that fitness walking does not require a commute to a health club, the author stresses the convenience of this form of exercise. The paragraph also states that fitness walking will result in a good workout. Choice a is incorrect because no comparison to weight lifting is made. Choice b may seem like a logical answer, but the paragraph only refers to people who are fitness walkers, so for others, a health club might be a good investment. Choice c is not in the passage. Although choice e seems logical, the paragraph does not indicate that the wrong shoes will produce major injuries.