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?

1. Even homeowners whose yards do not have water-conserving landscapes can conserve water by installing water-saving devices in their homes.
2. A conventional landscape generally requires a much greater expenditure on fertilizer and herbicide than does a water-conserving landscape.
3. A significant proportion of the residents of the city live in buildings that do not have yards.
4. It costs no more to put in water-conserving landscaping than it does to put in conventional landscaping.
5. 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！！

question是哪一个反对criticism的论证.

B provides additional information as of why conversion is good.