Q15: Brochure: Help conserve our city’s water supply. By converting the landscaping in your yard to a water-conserving landscape, you can greatly reduce your outdoor water use. A water-conserving landscape is natural and attractive, and it also saves you money. Criticism: For most people with yards, the savings from converting to a water-conserving landscape cannot justify the expense of new landscaping, since typically the conversion would save less than twenty dollars on a homeowner’s yearly water bills. Which of the following, if true, provides the best basis for a rebuttal of the criticism? - Even homeowners whose yards do not have water-conserving landscapes can conserve water by installing water-saving devices in their homes.
- A conventional landscape generally requires a much greater expenditure on fertilizer and herbicide than does a water-conserving landscape.
- A significant proportion of the residents of the city live in buildings that do not have yards.
- It costs no more to put in water-conserving landscaping than it does to put in conventional landscaping.
- Some homeowners use more water to maintain their yards than they use for all other purposes combined.
问题看的不是很明白，是问以下哪个为criticism的论证提供了basis，还是哪一个反对criticism的论证？ 另外b的答案为什么可以．我做的时候把用排除法排了前四个，然后发现第５个也不太对．望nn指点！！ | 
